Musnad Ahmad 1060:61

Muhammad ibn Ubayd narrated to us, Muhammad ibn Ishaq narrated to us, from Talha ibn Ubayd Allah—meaning Ibn Kurayz—from an elder from the people of Makkah, from the Quraysh, from Abu Ayyub al-Ansari, who said: A man found a louse in his garment, so he took it to throw it into the mosque. The Messenger of Allah, peace and blessings of Allah be upon him, said to him: "Do not do that; return it to your garment until you exit the mosque."