Tanzil

Process

The Quran describes its original source as the “mother of the book” (umm al-kitāb), which resides with Allah, and also refers to this source as a “well-guarded tablet” (lawḥ mahfūz) and a “concealed book” (kitāb maknūn). The revelation to Muhammad is presented as being dictated by the angel Jabril, not by Allah directly, with Muhammad acting as a messenger. While the Quran descends, Allah Himself is never described as coming down in the Quran, though some ḥadīth mention Him moving from higher to lower heavens.

The basic units of revelation were short passages or verses (āyāt), later arranged into surahs under divine guidance, according to Muslim belief. Ibn Kathīr, in his tafsīr, cited a ḥadīth from Abd Allāh ibn ʿAbbās stating that Allah sent the Quran down all at once from the Preserved Tablet to the House of Might (Bayt al-ʿIzzah) in the lowest heaven, after which it came down in parts to Muhammad over twenty-three years based on incidents. Thus, the Quran descended in two stages: first, an inzāl from the Lawḥ al-Maḥfūẓ to the Bayt al-ʿIzzah on the Night of Destiny (Laylat al-qadr); second, a tanzīl from the Bayt al-ʿIzzah to the worldly realm, revealed piecemeal by Gabriel over twenty-three years. Ṭabāṭabāʾī explains that inzāl is a sudden act of sending down at once, while tanzīl is a gradual act of sending.

Some commentators believe the Quran was revealed to Muhammad twice: an immediate revelation on Laylat al-Qadr and the gradual revelation over twenty-three years, based on an interpretation of sūrah Al-Qadr:1. ʿAbd Allāh ibn ʿAbbās reports that the Quran descended in Ramaḍān, on the Laylat al-Qadr, in one lay down.

Asbab al-nuzul

The study of the circumstances under which particular verses were sent down is known as Asbāb al-nuzūl, or 'occasions of revelation'. Abu al-Hassan Alī bin Ahmad al-Wahidī an-Naisabūrī, considered the father of this field, argued that understanding these reasons was essential for resolving apparent inconsistencies in the Quran. According to al-Suyūṭī, revelations came down for two basic reasons: divine initiative, such as the first revelation at Ḥirāʾ or the verses calling for the Fast of Ramaḍān, and to address a situation directly or answer a question, as with sūrah al-Anfāl concerning the aftermath of the Battle of Badr.

Scholars like al-Wahidī and al-Zarkashī held that the asbāb can only be determined through direct transmission from witnesses of the revelation, not through independent reasoning or legal consensus, relying on ḥadīth reports from canonical collections, Islamic historiography, or tafsīr works. However, such ḥadīth on asbāb very frequently contradict each other, which calls into question the reliability of the genre.