Bayhaqi 1838 — s on the adhan and iqamah -- Chapter: Facing the qiblah

It is narrated from Sayyiduna Mu'adh bin Jabal (may Allah be pleased with him) that the prayer went through three stages: first the stage of the qiblah, then the prayer of the latecomer (masbuq), and in between them the stage of the adhan. Then he said: The people used to gather for the prayer and inform one another; then they struck the clapper (naqus), or he said: they were about to strike the clapper. Then a man named Abdullah bin Zayd (may Allah be pleased with him) came to the Prophet (peace and blessings be upon him) and said: O Messenger of Allah, I was in light sleep, and I saw a man wearing two green garments; he stood up, faced the qiblah and said: 'Allahu akbar, Allahu akbar' (Allah is the Greatest, Allah is the Greatest), until he had finished the adhan, saying each phrase twice. Then at the end of his adhan he said: 'Allahu akbar, Allahu akbar, la ilaha illallah' (Allah is the Greatest, Allah is the Greatest, there is no god but Allah). Then he paused for a while, then stood and said the same, except that he added: 'Qad qamatis-salah, qad qamatis-salah' (The prayer has begun, the prayer has begun). The Messenger of Allah (peace and blessings be upon him) said: "Teach it to Bilal (may Allah be pleased with him)." The first one to give the adhan was Sayyiduna Bilal (may Allah be pleased with him). Then Sayyiduna Umar bin al-Khattab (may Allah be pleased with him) came and said: O Messenger of Allah, the same figure came round to me as came round to Abdullah bin Zayd (may Allah be pleased with him), but he reached you before me.
A group narrated it with this meaning from al-Mas'udi, except that Abd al-Rahman bin Abi Layla did not mention Mu'adh, so it is mursal (with a broken chain).