Musnad Ahmad 32:281

Yazid ibn Harun narrated to us, Hammad informed us, from Thabit, from Anas: "The Messenger of Allah (peace and blessings of Allah be upon him) was playing with the boys. A comer came to him, took him, and split his abdomen. He extracted a blood clot from it and threw it away, saying: 'This is the portion of Satan from you.' Then he washed it in a basin of gold with Zamzam water. Then he joined it back together. The boys ran to his wet nurse saying: 'Muhammad has been killed! Muhammad has been killed!' So they went to meet the Messenger of Allah (peace and blessings of Allah be upon him), and his color had changed." Anas said: "We used to see the mark of the needle on his chest."