Musnad Ahmad 1280:1

'Affan narrated to us, Shu'bah narrated to us, from Khubayb, who said: I heard my paternal aunt say—and she had performed Hajj with the Prophet, peace and blessings of Allah be upon him—she said: The Messenger of Allah, peace and blessings of Allah be upon him, used to say: "Indeed, Ibn Umm Maktum calls the adhan at night, so eat and drink until Bilal calls; or indeed, Bilal calls the adhan at night, so eat and drink until Ibn Umm Maktum calls." And this one would ascend and that one would descend, so we would hold onto him and say: "Stay as you are until we finish our suhur."