Musnad Ahmad 759:3

Aswad ibn Amir narrated to us, Zuhayr narrated to us, from Abdullah ibn Isa, from Isa ibn Abd al-Rahman ibn Abi Layla, from Abi Layla, that he was with the Messenger of Allah (may Allah bless him and grant him peace), and upon his stomach was al-Hasan or al-Husayn—Zuhayr was uncertain. He said: He urinated until I saw his urine on the stomach of the Messenger of Allah (may Allah bless him and grant him peace) like streaks. He said: So we jumped toward him. He said: Then he said, "Leave my son, or do not frighten my son." He said: Then he called for water and poured it over it. He said: Then he took a date from the dates of charity. He said: So he put it into his mouth. He said: Then the Messenger of Allah (may Allah bless him and grant him peace) pulled it out from his mouth.