Sayyiduna Shayban (may Allah be pleased with him) says: I entered the mosque, called the adhan and sat aside in a corner. The Messenger of Allah (peace and blessings be upon him) said to me: "O Abu Yahya!" I said: "Yes." He (peace and blessings be upon him) said: "Come closer and eat." I said: "I intend to fast." He (peace and blessings be upon him) said: "I too intend to fast, but our muezzin has something wrong with his eyesight, or something else, and he called the adhan before dawn broke."
Ash'ath bin Sawwar is alone in narrating this hadith. If it is authentic, it seems that the adhan of Sayyiduna Ibn Umm Maktum (may Allah be pleased with him) took place before dawn, so the Messenger of Allah (peace and blessings be upon him) did not refrain from eating. On the basis of what we have mentioned, the reports agree and do not differ; and success is from Allah.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيام / 8023