Musnad Ahmad 32:2125

'Affan narrated to us, Hammad narrated to us, he said: Thabit informed us, from Anas, "That the Messenger of Allah, may Allah bless him and grant him peace, was approached by Gabriel, peace be upon him, while he was playing with the boys. He took him and laid him down, then he split open his chest, extracted a blood clot from it, and said: 'This is the portion of Satan in you.' Then he washed it in a basin of gold with Zamzam water, then he joined it together and returned it to its place. The boys came running to his mother—meaning his wet nurse—and said: 'Indeed, Muhammad has been killed.' They went to meet him, and he was pale in color." Anas said to me: "And I used to see the mark of the stitching on his chest." And perhaps Hammad said: "That the Messenger of Allah, may Allah bless him and grant him peace, was approached by someone."