Musnad Ahmad 31:663

Yunus and Surayj narrated to us, they said: Fulayh narrated to us, from Ayyub ibn Habib, from Abu al-Muthanna al-Juhani, who said: I heard Marwan while he was asking Abu Sa’id al-Khudri: Did the Messenger of Allah, peace and blessings of Allah be upon him, forbid breathing into one’s vessel while drinking? Abu Sa’id said: Yes. A man said to him: O Messenger of Allah, I cannot quench my thirst in one breath. He said: "Then when you breathe, move the vessel away from your face." He said: I see dirt in it, so should I blow into it? He said: "When you see it, then pour it out, and do not blow into it."