Musannaf Ibn Abi Shayba 22:279

Mu'awiyah ibn Hisham narrated to us, he said: 'Ammar ibn Ruzayq narrated to us, from al-A'mash, from Hassan ibn Abi al-Ashras, from Sa'id ibn Jubayr, from Ibn 'Abbas regarding His saying: "Indeed, We sent it down during the Night of Decree." He said: It was raised to Gabriel on the Night of Decree in its entirety, then it was raised to the House of Might (Bayt al-'Izzah). Then he began to send it down gradually.