And the infidels said why the Quran was not sent down on them all at once? We have thus sent it down gradually that We may strengthen your heart there with and We recited it with gradual recitation.[25:32]
It is narrated on the authority of Yahya b. Ya'mur and Humaid b. 'Abdur-Rahman that they said: We met Abdullah b. 'Umar and we discussed about the Divine Decree, and what they talked about it and he narrated the hadith that has been transmitted by 'Umar (may Allah be pleased with him) from the Apostle (may peace be upon him). There is a slight variation in that.