It was narrated from Zahdam that:Some chicken was brought to Abu Musa and a man moved away from the people. He said: "What is the matter with you?" He said: "I saw it eating something that I consider filthy, and I swore I would not eat it." Abu Musa said: "Come and eat, for I saw the Messenger of Allah eating it." And he told him to offer an expiation for his vow (Kafarat Al-Yamin)

English translation · Sunan an-Nasa'i