Preposition (harf jarr)

A harf jarr never stands alone. It leans on the ism after it, and that ism goes into jarr — which is one of only two things that ever puts an ism in jarr, the other being the idafa. So a preposition is one of the most reliable signposts in a Quranic phrase: see the harf, and you know the next word is in jarr before you have read it.

What follows need not be a noun in the English sense. بِهِ is a pronoun in jarr, بِهَٰذَا a demonstrative, بِمَا نَسُوا a whole clause folded into a masdar. All of them are isms, and that is the word the definition uses.

You will meet this same case called الخَفْض (khafd) in older books and in the Kufan tradition. It is not a different thing — khafd and jarr are two names for one case.

All seventeen do one grammatical thing: the ism after them goes into jarr. What differs is the meaning, and they fall into a few natural sets. The oath — وَ and تَ swear, تَ only with the name of Allah. بِ swears too, alongside everything else it does. Since — مُنْذُ and مُذْ, both for a stretch of time. Except — خَلَا، عَدَا، حَاشَا, which are also the words of exception and can work as verbs. رُبَّ — 'many a', always before an indefinite. The everyday set — مِنْ، إِلَى، عَنْ، عَلَى، فِي، بِ، لِ، كَ، حَتَّى — what you meet on almost every page. Classical grammarians list 17 hurūf al-jarr. The Quran uses 11 of them.

What happens when a harf of jarr meets an attached pronoun?

The pronoun simply takes the noun's place: بِهِ (with it), عَلَيْهِمْ (upon them), لَكَ (for you). Recognising harf + pronoun combinations unlocks an enormous amount of Quranic text.