Musnad Ahmad 32:335

Abu Amir narrated to us, Fulayh narrated to us, from Hilal ibn Ali, from Anas, who said: We attended the funeral of a daughter of the Messenger of Allah, may Allah bless him and grant him peace, and the Messenger of Allah, may Allah bless him and grant him peace, was sitting by the grave. I saw his eyes shedding tears. He said: "Is there any man among you who did not commit sexual intercourse last night?" Abu Talha said: "Yes, I." He said: "Then descend [into the grave]." He said: So he descended into her grave.