تَنزيلُ الكِتابِ مِنَ اللَّهِ العَزيزِ الحَكيمِ

The [gradual] sending down of the book is from Allah, the all-mighty, the all-wise.

EXEGESIS

Since tanzīl in verse 1 is used interchangeably and synonymously with inzāl in verse 2, it can be concluded that tanzīl does not concern the gradual descent of the Quran in particular. Rather, the focus of discussion is that 1. The book is sent from Allah, the all-mighty, the all-wise. 2. It is sent with the truth (verse 2).

There is much similarity between the opening verse of this chapter and the opening verses of the chapters that start with disjointed letters. They all concern the descent of the Quran and revelation. In fact, the first verse here is identical to the second verse in chapters 45 and 46. This might have been the cause for the alleged confusion in the codex of Ubayy ibn Kaʿb in which al-Zumar was included in with the Ḥawāmīm.

EXPOSITION

This chapter starts with the assertion that the Quran is sent from God. Since it is sent from a sublime and all-mighty source, the book is also sublime and unassailable (41:41); and since it is sent from an all-wise source, the book is also wise (36:2). It then follows that the key to connect to divine might and wisdom is to follow the book that is from Allah, the all-mighty, the all-wise.^{‎[1]Qaraati, 8/139.}

What the Quran requires of its audience in the following verses – to obey and worship God – is backed and supported by these three arguments presented concisely in this verse: 1. This book is sent from God. 2. The sender is all-mighty (and so is the book). 3. The sender is all-wise (and so is the book).

[1] Qaraati, 8/139.