Sayyiduna Ibn Abbas (may Allah be pleased with them both) said concerning (the verse) "Indeed, We sent it down on the Night of Decree" [Surah al-Qadr: 1]: "The Qur'an was sent down all at once until it was placed in the House of Honour (Bayt al-'Izzah) in the lowest heaven. Then Sayyiduna Jibril (peace be upon him) brought it down to Muhammad (peace and blessings be upon him) in response to matters that arose in the lowest heaven, and Sayyiduna Jibril (peace be upon him) brought it down to Muhammad (peace and blessings be upon him) in response to the words of the servants and their deeds."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12329