Musnad Ahmad 1153:840

Ibrahim ibn Ishaq narrated to us, he said: Ibn al-Mubarak narrated to us, from Yunus, from al-Zuhri, from Abu Salamah, from Aisha, she said: The Messenger of Allah, peace and blessings of Allah be upon him, said: "O Aisha, this is Gabriel, peace be upon him, and he is greeting you with peace." I said: "Upon him and upon you be peace, and the mercy of Allah and His blessings. You see what we do not see, O Messenger of Allah."