(It is) a Qur'an which We have divided (into parts from time to time), in order that thou mightest recite it to men at intervals: We have revealed it by stages. Al-Isra 17:106 ⧉
Tafsir:
The Quran is a declaration of pristine truth. But this pristine truth is what is least acceptable to man. For this reason God did not burden the preacher of truth with the responsibility of forcing people to believe in him. All that is desired of him is that he should communicate the truth to the addressee to the fullest possible extent. The Quran makes full allowances for the weaknesses of the addressees. Hence the Quran has been revealed at intervals, so that those who are serious about it, may have time to fully understand it; slowly and steadily it may become a part and parcel of their thoughts and actions.