Musnad Ahmad 790:141

Isma'il ibn Ibrahim narrated to us, from Muhammad ibn al-Zubayr, my father narrated to me that he met a man in Makkah, and he narrated to him from 'Imran ibn Husayn, from the Prophet, peace and blessings of Allah be upon him, that he said: "There is no vow in anger, and its expiation is the expiation of an oath."