Pronouns in Arabic are indeclinable (not affected by noun cases). We differentiate two categories of pronouns in Arabic:

• Detached pronouns / الضَمائِر المُنْفَصِلة
• Attached pronouns / الضَمائِر المُتَّصِلة

Generally speaking, detached pronouns are assumed to be in the nominative case (even though they are indeclinable), whereas attached pronouns are rather in either the accusative or genitive cases.

Detached Pronouns / الضَمائِر المُنْفَصِلة

Note: The pronouns أَنْتُمْ and هُمْ both take a ḍamma instead of a sukūn when followed by a noun bearing the definite article ال

هُمُ الناجِحُونَ

They are the successful ones

Attached Pronouns / الضَمائِر المُتّصِلة

Note: The attached pronouns ـكُمْ and ـهُمْ work exactly as the detached one, which means they both take a ḍamma instead of a sukūn when followed by a noun bearing the definite article ال

Note 2: 3rd person pronouns ـهُمْ / ـهُنَّ / ـهُ all take the kasra if the word they are attached to is in genitive case or ends with a ي.

The book is at his house	الكِتابُ في بَيْتِهِ
There’s faith inside of them	فِيهِمْ إِيمانٌ

Note 3: The first person singular pronoun ـِي erases the final short vowel of the noun or the preposition it is attached to and replace it by a kasra, except if the word ends with a long vowel. In the later case, the ي will have to bear the fatḥa

My restaurant	مَطْعَمٌ + ـِي  = مَطْعَمِي
My level	مُستَوى + ـِي  = مُسْتوايَ
On me	عَلى + ـِي  = عَليَّ

The attached pronouns work as suffixes which can follow: