17:106
وَقُرْءَانًا فَرَقْنَـٰهُ لِتَقْرَأَهُۥ عَلَى ٱلنَّاسِ عَلَىٰ مُكْثٍ وَنَزَّلْنَـٰهُ تَنزِيلًا
waqur'ānan faraqnāhu litaqra-ahu ʿalā l-nāsi ʿalā muk'thin wanazzalnāhu tanzīlan
it is a recitation that We have revealed in parts, so that you can recite it to people at intervals; We have sent it down little by little.
And (it is) a Qur’ân which We have divided (into parts), in order that you might recite it to men at intervals. And We have revealed it by stages (in 23 years).