Sunan Abu Dawood, Chapter: Purification (Kitab Al-Taharah)

One night I became the guest of the Prophet (peace_be_upon_him). He ordered that a piece of mutton be roasted, and it was roasted. He then took a knife and began to cut the meat with it for me. In the meantime Bilal came and called him for prayer. He threw the knife and said: What happened! may his hands be smeared with earth! He then stood for offering prayer. Al-Anbari added: My moustaches became lengthy. He trimmed them by placing a took-stick; or he said: I shall trim your moustaches by placing the tooth-stick there.