Musannaf Ibn Abi Shayba 29:90

Yahya ibn Sa'id al-Qattan narrated to us, from Sufyan, from al-Rukayn, from his father, who said: We were with Salman ibn Rabi'ah in Balanjar. I saw the crescent of Shawwal on the twenty-ninth day, on the night of the thirtieth, in the forenoon. He said: So he said, "Show it to me," and I showed it to him. Then he commanded the people, and they broke their fast.