Musnad Ahmad 32:1134

Yazid narrated to us, Humayd narrated to us, from Anas, that a young son of Umm Sulaym—who was called Abu Umayr—had a small bird (nughayr). Whenever the Messenger of Allah (peace be upon him) entered upon her, he would joke with him. He saw him sad, so he said, "What is the matter with Abu Umayr?" They said, "O Messenger of Allah, his small bird has died." He said, so he began to say, "O Abu Umayr, what did the small bird do?"