Sahih Bukhari Volume 4, Book 52, Hadith Number 135.

Narated By Abu Musa : Abu ‘Amir was hit with an arrow in his knee, so I went to him and he asked me to remove the arrow. When I removed it, the water started dribbling from it. Then I went to the Prophet and told him about it. He said, “O Allah! Forgive ‘Ubaid Abu ‘Amir.”