Causal Particle · فاء السببيةThe causal فَ ties an action to the reason behind it — 'so'. Because Musa asked, therefore: We said. L14 · R5

Verb · فعلA verb is a word for an action or happening that is always tied to a time — past, present/future, or a command. قُلْ speaks of an action already carried out: '[so] We said', from the root قول: to say, speak, tell. L1 · R7

Past Tense Verb · فعل ماضٍA past-tense verb describes an action already completed — and it shows who by a small ending fastened to the verb's tail. On فَقُلْنَا that ending is نَا, telling exactly who is meant: '[so] We said', from the root قول: to say, speak, tell. L8 · R2

Weak Verb · فعل معتلA weak verb is a verb that carries و or ي — the 'weak' letters, which love to soften into long vowels or vanish — among its root letters. The root of قُلْ is قول: to say, speak, tell — and its middle letter is the weak و, so the weakness sits in the middle of the root. L24 · R4

Attached Pronoun · ضمير متصلAn attached pronoun is a mini-word for 'I / you / he' that cannot stand alone — it is glued onto the end of another word, and each form carries within it exactly who is meant. نَا · 'us/our' is fastened to the tail of the verb here — فَقُلْنَا — naming the one who did the action. L3 · R6

Doer (Fa'il) · فاعلThe doer is the one performing the action, standing in the nominative — the doer's form, usually a ḍammah ـُ, a small curl above the last letter. The ending نَا is that doer, 'We'; an attached pronoun keeps one fixed shape, so no ḍammah appears, but the role it fills is the nominative one. L9 · R4

Verb · فعلA verb is a word for an action or happening that is always tied to a time — past, present/future, or a command. ٱضْرِب is a command: 'Strike', from the root ضرب: to strike, set forth (examples), travel. L1 · R7

Imperative Verb · فعل أمرAn imperative verb is a direct command addressed to 'you', formed from the present-tense verb by removing its opening prefix and adding a helping ٱ when what remains starts with a vowelless letter. ٱضْرِب shows that helping ٱ at its front — a command to one man, Musa: strike! L10 · R1

Preposition · حرف جرThe small prefix بِّ at the front of بِّعَصَاكَ is a preposition — a little helper word meaning 'in/with' that relates one thing to another. A preposition 'pulls' the word that follows it into the genitive relationship — the 'of / in / with' role a word plays after such a little helper — though not every word shows that role with the same visible ending. L4 · R1

Noun · اسمA noun is a word that names a person, place, thing, or idea. عَصَا names such a thing: 'with your staff', from the root عصو: staff. L1 · R6

Masculine Noun · اسم مذكرArabic treats every noun — every naming word — as grammatically 'he' or 'she'. بِّعَصَاكَ carries no feminine marker — no ة at its end, no final ى, no اء — so it takes the default and is treated as 'he': a masculine noun. L2 · R3

Genitive · مجرورThe genitive is the ending a naming word takes after a preposition, usually shown by a kasrah ـِ — a small slanted stroke below the last letter. عَصَا ends in the long letter ا, which carries no vowel mark, so nothing shows on the page — the genitive, forced by the بِّ before it, is the role the word fills. L2 · R12

Attached Pronoun · ضمير متصلAn attached pronoun is a mini-word glued onto the end of another word. The ending كَ on بِّعَصَاكَ is such a suffix, standing for 'your': YOUR staff. L3 · R6

Possessive (Idafa) · مضاف إليهA possessive (iḍāfah) chains two naming words into an 'of' phrase, and the owner comes second, taking the genitive — the owner's ending, usually a kasrah ـِ, a small stroke below the last letter. The ending كَ fills that owner slot: 'the staff OF you'; a pronoun keeps one fixed written shape, so the genitive is the role it fills. L5 · R5

Definite Article · أل التعريفThe definite article is the prefix ٱلْ at the front of a noun (a naming word); it means 'the' — one specific, known one. The letter after it is a 'moon' letter — a letter not made in the same part of the mouth as ل — so the ل of the prefix keeps its own sound, both written and heard, resting with the sukūn ـْ (a small circle written above the letter): ٱلْحَجَرَ. L2 · R9

Noun · اسمA noun is a word that names a person, place, thing, or idea. حَجَرَ names such a thing: 'the stone', from the root حجر: stone; to forbid, prevent; barrier, partition; mind. L1 · R6

Masculine Noun · اسم مذكرArabic treats every noun — every naming word — as grammatically 'he' or 'she'. ٱلْحَجَرَ carries no feminine marker — no ة at its end, no final ى, no اء — so it takes the default and is treated as 'he': a masculine noun. L2 · R3

Accusative · منصوبThe accusative is the ending a naming word takes when the action lands on it, shown by a fathah ـَ — a small slanted stroke above the letter. حَجَرَ ends in that fathah ـَ. L2 · R11

Direct Object · مفعول بهThe direct object is the thing the action lands on, standing in the accusative — the landed-on form, here the fathah ـَ above its last letter. The stone is what the commanded strike lands on. L9 · R3

Resumptive Particle · حرف استئنافA resumptive particle is a وَ or فَ that begins a fresh statement after a pause or a shift of topic — it starts the speech anew rather than adding one more item to a list. The prefix فَ · 'then' at the front of فَٱنفَجَرَتْ opens such a fresh start. L14 · R1

Verb · فعلA verb is a word for an action or happening that is always tied to a time — past, present/future, or a command. ٱنفَجَرَتْ speaks of an action already carried out: 'Then gushed forth', from the root فجر: to split open, burst forth, dawn; wickedness. L1 · R7

Past Tense Verb · فعل ماضٍA past tense verb describes an action already completed, and who did it is shown by an ending added to the verb. The ending تْ — the 'she' marker, wearing the sukūn ـْ, a small circle meaning no vowel follows — sits on ٱنفَجَرَتْ, agreeing with the springs, spoken of as 'she': 'it gushed forth', already done. L8 · R2

Form VII Verb · اِنْفَعَلَA Form VII verb adds اِنـ to the front of the root, meaning the action simply happens to the subject — اِنْفَجَرَ 'burst forth' is a textbook case. ٱنفَجَرَتْ shows that ٱن at its front: the water did not split anything — it itself burst out. L13 · R3

Particle · حرفA particle is a small helper word of one to three letters that works like glue — it connects or adjusts other words rather than naming something or describing an action, and it can never be the one a sentence is about. مِنْ · 'from/of' is such a helper. L1 · R9

Preposition · حرف جرA preposition is a little helper word that relates one thing to another; Arabic keeps a short list of them — small words like فِي 'in', مِنْ 'from', and عَلَىٰ 'on'. مِنْ · 'from/of' is one of these relation-words. L4 · R2

Attached Pronoun · ضمير متصلAn attached pronoun is a mini-word for 'me / us / them' that cannot stand alone — it is glued onto the end of another word, and each form carries within it exactly who is meant. هُ · 'him/his' hangs on the little relation-word in مِنْهُ, governed by the word it is fastened to. L3 · R6

Noun · اسمA noun is a word that names a person, place, thing, or idea. ٱثْنَتَا names such a thing: '(of)', from the root ثني: to double, make two, second; twice, pair. L1 · R6

Feminine Noun · اسم مؤنثA feminine noun is a naming word Arabic treats as grammatically 'she'. Most feminine nouns wear a visible marker — a ة at the end, a final ى, or اء — but ٱثْنَتَا shows none of these: it is one of the words Arabic simply knows as feminine, learned with the word itself: '(of)'. L2 · R2

Dual Noun · مثنىA dual noun refers to exactly two of something and carries its role in its ending — ـَانِ for the nominative, ـَيْنِ for the accusative and genitive. ٱثْنَتَا wears the long ا of that dual ending (its ن is not written in this joined number phrase): 'two', paired with 'ten' to make twelve. L2 · R5

Nominative · مرفوعThe nominative is the ending a naming word takes as the subject of its sentence, usually shown by a ḍammah ـُ — a small curl above the last letter. ٱثْنَتَا shows no ḍammah — the long ا is the shape this two-word wears in the subject role — so the nominative here is the role it fills, not a curl on show. L2 · R5

Doer (Fa'il) · فاعلThe doer is the one performing the action in a verb-first sentence, standing in the nominative — the doer's form, usually a ḍammah ـُ above the last letter, shown on this dual by its ا ending instead. The twelve springs are what did the gushing. L9 · R2

Noun · اسمA word that ends with the tā marbūtah ة is a noun, a naming word. عَشْرَةَ names 'ten', from the root عشر — ten. L1 · R3

Feminine Noun · اسم مؤنثA feminine noun is a naming word Arabic treats as grammatically 'she', most often marked by a ة — the round 'tied tā' — at its end. عَشْرَةَ carries exactly that round ة at its end, so it is treated as feminine: 'twelve'. L2 · R1

Genitive · مجرورThe genitive is the owner's ending in an 'of' pairing, usually shown by a kasrah ـِ — a small slanted stroke below the last letter. عَشْرَةَ fills a genitive role here, but what is written on its end is a fathah ـَ — a small stroke above the ة — the fixed shape this word keeps inside the joined number 'two-ten'; the genitive is the role, not a mark on show. L2 · R14

Possessive (Idafa) · مضاف إليهA possessive (iḍāfah) chains two naming words into an 'of' phrase, and the second fills the owner slot in the genitive — usually a kasrah ـِ below the last letter. عَشْرَةَ 'ten' stands as that second half of the pair ٱثْنَتَا عَشْرَةَ, 'two-of-ten' — twelve; on this joined number word the written ending stays a fathah ـَ, so the genitive is the role it fills. L5 · R5

Noun · اسمA noun is a word that names a person, place, thing, or idea. عَيْنًا names such a thing: 'springs', from the root عين: eye, spring of water. L1 · R6

Feminine Noun · اسم مؤنثA feminine noun is a naming word Arabic treats as grammatically 'she'. Most feminine nouns wear a visible marker — a ة at the end, a final ى, or اء — but عَيْنًا shows none of these: it is one of the words Arabic simply knows as feminine, learned with the word itself: 'springs'. L2 · R2

Indefinite Noun · نكرةAn indefinite noun means 'a' or 'any' one of something — no particular one — and it never wears the definite article ال ('the'); instead it shows this with tanwīn, a doubled end-vowel mark. عَيْنًا carries the tanwīn ـً — the fathah ـَ doubled — marking it as unspecified: 'springs'. L2 · R8

Accusative · منصوبThe accusative is an ending shown by a fathah ـَ — a small slanted stroke above the letter — doubled to tanwīn ـً when the word is indefinite. عَيْنًا carries that doubled fathah ـً. L2 · R11

Specification (Tamyīz) · التمييزThe tamyīz is an indefinite accusative naming word added to pin down what a vague statement is about, and it appears after numbers to specify the counted unit. 'Twelve' of what? عَيْنًا answers: springs — written as a single 'spring' with the doubled fathah ـً, the shape Arabic uses for the counted unit after such numbers. L21 · R13

Certainty Particle (قَدْ) · حرف تحقيقThe certainty particle قَدْ, placed before a past tense verb, stresses that the action truly happened. Here it stands before عَلِمَ 'knew': every tribe certainly knew its own spring. L20 · R16

Verb · فعلA verb is a word for an action or happening that is always tied to a time — past, present/future, or a command. عَلِمَ speaks of an action already carried out: 'knew', from the root علم: to know, knowledge. L1 · R7

Past Tense Verb · فعل ماضٍA past-tense verb describes an action already completed. Its plain base shape — the shape Arabic uses for a single 'he' — carries no who-ending glued to its tail, and عَلِمَ is exactly that bare base: 'knew', from the root علم: to know, knowledge. L8 · R1

Noun · اسمA noun is a word that names a person, place, thing, or idea. كُلُّ names such a thing: 'all', from the root كلل: entirely, totally, all, everyone, each one, whole. L1 · R6

Masculine Noun · اسم مذكرArabic treats every noun — every naming word — as grammatically 'he' or 'she'. كُلُّ carries no feminine marker — no ة at its end, no final ى, no اء — so it takes the default and is treated as 'he': a masculine noun. L2 · R3

Nominative · مرفوعThe nominative is the ending a naming word takes as the subject of its sentence, shown by a ḍammah ـُ — a small curl above the last letter. كُلُّ ends in that ḍammah ـُ, sitting atop its doubled final letter. L2 · R10

Doer (Fa'il) · فاعلThe doer is the one performing the action in a verb-first sentence, standing in the nominative — shown here by the ḍammah ـُ on كُلُّ. 'Every group of people' is who did the knowing. L9 · R2

Noun · اسمA noun is a word that names a person, place, thing, or idea. أُنَاسٍ names such a thing: '(the) people', from the root انس: man. L1 · R6

Masculine Noun · اسم مذكرArabic treats every noun — every naming word — as grammatically 'he' or 'she'. أُنَاسٍۢ carries no feminine marker — no ة at its end, no final ى, no اء — so it takes the default and is treated as 'he': a masculine noun. L2 · R3

Plural Noun · جمعA plural noun refers to three or more, made either by adding an ending or by reshaping the word from the inside — a 'broken' plural. أُنَاس is such a reshaped plural: people, many of them, with no added plural ending. L2 · R6

Indefinite Noun · نكرةAn indefinite noun means 'a' or 'any' one of something — no particular one — and it never wears the definite article ال ('the'); instead it shows this with tanwīn, a doubled end-vowel mark. أُنَاسٍ carries the tanwīn ـٍ — the kasrah ـِ doubled — marking it as unspecified: '(the) people'. L2 · R8

Genitive · مجرورThe genitive is the ending a naming word takes as the owner in an 'of' phrase, shown by a kasrah ـِ — a small slanted stroke below the last letter — doubled to tanwīn ـٍ when the word is indefinite. أُنَاسٍ ends in that doubled kasrah ـٍ. L2 · R12

Possessive (Idafa) · مضاف إليهA possessive (iḍāfah) chains two naming words into an 'of' phrase, and the owner comes second, taking the genitive — shown here by the doubled kasrah ـٍ on أُنَاسٍ. It fills that owner slot after كُلُّ: 'every ONE OF the peoples' — each tribe. L5 · R5

Noun · اسمA noun is a word that names a person, place, thing, or idea. مَّشْرَبَ names such a thing: 'their drinking place', from the root شرب: to drink, drinking. L1 · R6

Masculine Noun · اسم مذكرArabic treats every noun — every naming word — as grammatically 'he' or 'she'. مَّشْرَبَهُمْ carries no feminine marker — no ة at its end, no final ى, no اء — so it takes the default and is treated as 'he': a masculine noun. L2 · R3

Accusative · منصوبThe accusative is the ending a naming word takes when the action lands on it, shown by a fathah ـَ — a small slanted stroke above the letter. مَّشْرَبَ ends in that fathah ـَ. L2 · R11

Direct Object · مفعول بهThe direct object is the thing the action lands on, standing in the accusative — the landed-on form, here the fathah ـَ above the ب. The drinking place is what each tribe's knowing landed on. L9 · R3

Attached Pronoun · ضمير متصلAn attached pronoun is a mini-word glued onto the end of another word. The ending هُمْ on مَّشْرَبَهُمْ is such a suffix, standing for 'their': THEIR drinking place. L3 · R6

Possessive (Idafa) · مضاف إليهA possessive (iḍāfah) chains two naming words into an 'of' phrase, and the owner comes second, taking the genitive — the owner's ending, usually a kasrah ـِ, a small stroke below the last letter. The ending هُمْ fills that owner slot: 'the drinking place OF them'; a pronoun keeps one fixed written shape, so the genitive is the role it fills. L5 · R5

Verb · فعلA verb is a word for an action or happening that is always tied to a time — past, present/future, or a command. كُلُ is a command: 'Eat', from the root اكل: to eat, consume. L1 · R7

Imperative Verb · فعل أمرAn imperative verb is a direct command addressed to 'you', formed from the present-tense verb by removing its opening prefix. كُلُوا۟ is that command shape aimed at a group — its ending وا۟ points the order at 'you all': eat! L10 · R1

Hamzated Verb · فعل مهموزA hamzated verb has a hamza (ء) as one of its root letters, and in the command shape that hamza may be cut away — كُلْ 'Eat!' from أَكَلَ is the classic case. كُلُوا۟ is exactly that trimmed command: the root's opening hamza is gone, leaving only ك and ل on the page. L24 · R12

Attached Pronoun · ضمير متصلAn attached pronoun is a mini-word for 'I / you / he' that cannot stand alone — it is glued onto the end of another word, and each form carries within it exactly who is meant. وا۟ · 'you all/your' is fastened to the tail of the verb here — كُلُوا۟ — naming the one who did the action. L3 · R6

Doer (Fa'il) · فاعلThe doer is the one performing the action, standing in the nominative — the doer's form, usually a ḍammah ـُ, a small curl above the last letter. The ending وا۟ is that doer, 'you all'; a pronoun keeps one fixed shape, so no ḍammah appears — the nominative is the role it fills. L9 · R4

Conjunction · حرف عطفThe prefix وَ at the front of وَٱشْرَبُوا۟ is a conjunction — a small joining word meaning 'and' — linking what follows to what came before; the word it joins in must stand in the same grammatical case as its partner before the joint — the same role in the sentence, even when the two words write that case with different endings. L4 · R4

Verb · فعلA verb is a word for an action or happening that is always tied to a time — past, present/future, or a command. ٱشْرَبُ is a command: 'and drink', from the root شرب: to drink, drinking. L1 · R7

Imperative Verb · فعل أمرAn imperative verb is a direct command addressed to 'you', formed from the present-tense verb by removing its opening prefix and adding a helping ٱ when what remains starts with a vowelless letter. ٱشْرَبُوا۟ shows that helping ٱ at its front, commanding a group — the ending وا۟ points the order at 'you all': drink! L10 · R1

Attached Pronoun · ضمير متصلAn attached pronoun is a mini-word for 'I / you / he' that cannot stand alone — it is glued onto the end of another word, and each form carries within it exactly who is meant. وا۟ · 'you all/your' is fastened to the tail of the verb here — وَٱشْرَبُوا۟ — naming the one who did the action. L3 · R6

Doer (Fa'il) · فاعلThe doer is the one performing the action, standing in the nominative — the doer's form, usually a ḍammah ـُ, a small curl above the last letter. The ending وا۟ is that doer, 'you all'; a pronoun keeps one fixed shape, so no ḍammah appears — the nominative is the role it fills. L9 · R4

Particle · حرفA particle is a small helper word of one to three letters that works like glue — it connects or adjusts other words rather than naming something or describing an action, and it can never be the one a sentence is about. مِن · 'from/of' is such a helper. L1 · R9

Preposition · حرف جرA preposition is a little helper word that relates one thing to another; Arabic keeps a short list of them — small words like فِي 'in', مِنْ 'from', and عَلَىٰ 'on'. مِن · 'from/of' is one of these relation-words. L4 · R2

Noun · اسمA noun is a word that names a person, place, thing, or idea. رِّزْقِ names such a thing: '(the) provision (of)', from the root رزق: to provide, necessaries of life, good, grant, bestow. L1 · R6

Masculine Noun · اسم مذكرArabic treats every noun — every naming word — as grammatically 'he' or 'she'. رِّزْقِ carries no feminine marker — no ة at its end, no final ى, no اء — so it takes the default and is treated as 'he': a masculine noun. L2 · R3

Genitive · مجرورThe genitive is the ending a noun (a naming word) takes after a preposition — a little word like 'in' or 'to' — and it is marked by a kasrah ـِ, a small slanted stroke written below the letter. رِّزْقِ stands right after such a little word, so its final letter carries exactly that kasrah ـِ: رِّزْقِ. L2 · R12

Noun · اسمA noun is a word that names a person, place, thing, or idea — and in Arabic this includes proper names. ٱللَّهِ is a proper name: 'Allah'. L1 · R6

Genitive · مجرورThe genitive is the ending a noun (a naming word) takes as the owner in an 'of' phrase, marked by a kasrah ـِ — a small slanted stroke written below the final letter. رِّزْقِ and ٱللَّهِ form such a pair, '(the) provision (of) Allah', and as the owner-word of that pair, ٱللَّهِ ends with exactly that kasrah ـِ. L2 · R12

Possessive (Idafa) · مضاف إليهArabic says 'of' by chaining two nouns — two naming words — directly together: رِّزْقِ ٱللَّهِ reads '(the) provision (of) — Allah'. The second word of such a chain, the owner, always takes the genitive — the after-'of' ending, shown by a kasrah ـِ, a small slanted stroke written below the letter — and ٱللَّهِ ends with exactly that kasrah ـِ. L5 · R5

Conjunction · حرف عطفThe prefix وَ at the front of وَلَا is a conjunction — a small joining word meaning 'and' — linking what follows to what came before; the word it joins in must stand in the same grammatical case as its partner before the joint — the same role in the sentence, even when the two words write that case with different endings. L4 · R4

Prohibition Particle · لا الناهيةThe prohibition لَا means 'do not!' — it commands someone NOT to act, and it trims the verb after it down to the cut-short jussive mood, the mood typically marked by a sukūn ـْ, a small circle above the verb's last letter. Here it forbids: do NOT act wickedly. L17 · R6

Verb · فعلA verb is a word for an action or happening that is always tied to a time — past, present/future, or a command. تَعْثَ is an action unfolding now: 'act wickedly', from the root عثو: to act wickedly, commit evil, act corruptly. L1 · R7

Present Tense Verb · فعل مضارعA present-tense verb is the verb shape that opens with one of the four present-tense prefixes أ ن ي ت; small helper words before it can bend its time and mood. تَعْثَ wears that present-tense shape, opening with exactly such a letter: 'act wickedly', from the root عثو: to act wickedly, commit evil, act corruptly. L8 · R3

Jussive Mood · الفعل المجزومA jussive verb is a present tense verb cut down because a trimming particle — like the forbidding لَا — stands before it; for the 'you all' shape the trimming shows by dropping the final نَ. تَعْثَوْا۟ has lost exactly that نَ: the 'do not!' before it cut it away. L10 · R5

The Five Verbs · الأفعال الخمسةThe Five Verbs are the five present-tense shapes whose ending closes with the letter ن — يَفْعَلَانِ, تَفْعَلَانِ, يَفْعَلُونَ, تَفْعَلُونَ, تَفْعَلِينَ. تَعْثَوْا۟ is one of them, but here its closing ن has dropped away — and for these five shapes that dropped ن is itself the grammar-sign: it marks the jussive mood, the bent form a governing word before it forces on the verb. L10 · R10

Weak Verb · فعل معتلA weak verb is a verb that carries و or ي — the 'weak' letters, which love to soften into long vowels or vanish — among its root letters. The root of تَعْثَ is عثو: to act wickedly, commit evil, act corruptly — and its last letter is the weak و, so the weakness sits at the very end of the root. L24 · R7

Attached Pronoun · ضمير متصلAn attached pronoun is a mini-word for 'I / you / he' that cannot stand alone — it is glued onto the end of another word, and each form carries within it exactly who is meant. وْا۟ · 'you all/your' is fastened to the tail of the verb here — تَعْثَوْا۟ — naming the one who did the action. L3 · R6

Doer (Fa'il) · فاعلThe doer is the one performing the action, standing in the nominative — the doer's form, usually a ḍammah ـُ, a small curl above the last letter. The ending وْا۟ is that doer, 'you all' — the ones forbidden from the wickedness; a pronoun keeps one fixed shape, so no ḍammah appears — the nominative is the role it fills. L9 · R4

Particle · حرفA particle is a small helper word of one to three letters that works like glue — it connects or adjusts other words rather than naming something or describing an action, and it can never be the one a sentence is about. فِى · 'in' is such a helper. L1 · R9

Preposition · حرف جرA preposition is a little helper word that relates one thing to another; Arabic keeps a short list of them — small words like فِي 'in', مِنْ 'from', and عَلَىٰ 'on'. فِى · 'in' is one of these relation-words. L4 · R2

Definite Article · أل التعريفThe definite article is the prefix ٱلْ at the front of a noun (a naming word); it means 'the' — one specific, known one. The letter after it is a 'moon' letter — a letter not made in the same part of the mouth as ل — so the ل of the prefix keeps its own sound, both written and heard, resting with the sukūn ـْ (a small circle written above the letter): ٱلْأَرْضِ. L2 · R9

Noun · اسمA noun is a word that names a person, place, thing, or idea. أَرْضِ names such a thing: 'the earth', from the root ارض: earth, land, ground. L1 · R6

Feminine Noun · اسم مؤنثA feminine noun is a naming word Arabic treats as grammatically 'she'. Most feminine nouns wear a visible marker — a ة at the end, a final ى, or اء — but أَرْضِ shows none of these: it is one of the words Arabic simply knows as feminine, learned with the word itself: 'the earth'. L2 · R2

Genitive · مجرورThe genitive is the ending a noun (a naming word) takes after a preposition — a little word like 'in' or 'to' — and it is marked by a kasrah ـِ, a small slanted stroke written below the letter. أَرْضِ stands right after such a little word, so its final letter carries exactly that kasrah ـِ: ٱلْأَرْضِ. L2 · R12

Noun · اسمA noun is a word that names a person, place, thing, or idea. مُفْسِدِينَ is such a naming word: 'spreading corruption', from the root فسد: to spread corruption, cause ruin, corrupters. L1 · R6

Masculine Noun · اسم مذكرArabic treats every noun — every naming word — as grammatically 'he' or 'she'. Even as a plural, مُفْسِدِينَ carries no feminine marker — no ة at its end, no final ى, no اء — so it takes the default and is a masculine noun; its ending is the 'sound' plural ending Arabic reserves for masculine nouns. L2 · R3

Plural Noun · جمعA plural noun refers to three or more of something. The sound masculine plural carries its role in its ending — ـُونَ for the nominative (the 'subject form', with the ḍammah ـُ sound), ـِينَ for the accusative and genitive (the 'object' and 'of' forms); مُفْسِدِينَ closes with exactly such an ending: not one, but a whole group. L2 · R6

Accusative · منصوبThe accusative is the landed-on ending, usually a fathah ـَ — a small stroke above the letter. Words with the ـُونَ/ـِينَ plural ending show their case differently: only the subject form ـُونَ looks distinct, and ـِينَ serves for the accusative. The ـِينَ on مُفْسِدِينَ is that accusative form here. L2 · R7

Active Participle · اسم فاعلAn active participle is a naming word built from a verb's root to name the doer of the action; for the derived verb families it begins with مُـ and carries a kasrah ـِ — a small stroke below — before its last root letter. مُفْسِدِ shows both: the مُ at its front and the kasrah on its س — 'those who DO the corrupting'. L11 · R3

Circumstantial (Hāl) · الحالThe ḥāl describes the state during the action, answering 'in what state?'; it takes the accusative — shown for this plural by its ـِينَ ending — and carries no ال. مُفْسِدِينَ names the forbidden state: do not act wickedly in the earth AS spreaders of corruption. L21 · R5