Musannaf Ibn Abi Shayba 2:7

Abu Bakr narrated to us, he said: Ghundar narrated to us, from Shu'bah, from 'Amr ibn Murrah, from Ibn Abi Layla, who said: Our companions narrated to us that a man from the Ansar came and said: "O Messenger of Allah, when I returned last night and saw your concern, I saw as if a man was standing upon the mosque wearing two green garments. He gave the adhan, then sat for a sitting, then stood and said the like of it, except that he said: 'The prayer has been established' (qad qamat al-salah). And were it not that you would say [otherwise], I would have said that I was awake, not asleep." The Prophet, peace and blessings of Allah be upon him, said: "Allah has shown you good." Then 'Umar said: "As for me, I have seen the like of what he saw, except that because I was preceded [in telling you], I felt shy." The Prophet, peace and blessings of Allah be upon him, said: "Command Bilal to give the adhan."