Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: "The Qur'an was separated from the Dhikr and placed in the House of Honour (Bayt al-'Izzah) in the lowest heaven. Then Sayyiduna Jibril (peace be upon him) kept bringing it down to the Prophet (peace and blessings be upon him), reciting it in measured portions."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12328