Sayyiduna Buraydah (may Allah be pleased with him) states: A man from the Ansar passed by the Prophet (peace and blessings be upon him) while he (the man) was grieved. The man used to prepare food, and people used to gather at his place. He entered his mosque and began to pray. While he was in that state, he dozed off, and someone came to him in his sleep and said, "I know what you are grieved about." Then the narrator related the whole story of the adhan. The Prophet (peace and blessings be upon him) said, "Abu Bakr has been told the like of what you have been told. Tell Bilal to give the adhan in this way."
Imam al-Tabarani recorded this narration in al-Mu'jam al-Awsat. Its chain contains a narrator about whom there has been criticism, but he is thiqah (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 1853