Musnad Ahmad 27:1049

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from 'Abdullah ibn Dinar: I heard Ibn 'Umar saying: The Messenger of Allah (ﷺ) said: "Indeed, Bilal calls the Adhan at night, so eat and drink until Bilal or Ibn Umm Maktum calls the Adhan."