Musnad Ahmad 1048:1

Isma'il narrated to us, Hajjaj al-Sawwaf narrated to me, from Yahya ibn Abi Kathir, from al-Hadrami ibn Lahiq, from a man of the Ansar, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "If one of you finds a louse in his garment, let him bundle it up, and do not throw it in the mosque."