Musnad Ahmad 32:2068

'Affan narrated to us, Mubarak ibn Fudalah narrated to us, al-Hasan narrated to us, Anas ibn Malik informed me, he said: I was with the Messenger of Allah, may Allah bless him and grant him peace, in his house, when a man came to him and said: "O Messenger of Allah, when is the Hour?" He said: "As for it, it is certainly coming. So what have you prepared for it?" He said: "By Allah, O Messenger of Allah, I have not prepared much work for it, except that I love Allah and His Messenger." He said: "Then you are with whom you love, and you shall have what you have anticipated." He said: Then the Messenger of Allah, may Allah bless him and grant him peace, stood up to pray. When he finished his prayer, he said: "Where is the one who asked about the Hour?" The man came, and the Messenger of Allah, may Allah bless him and grant him peace, looked at the house, and there was a boy from Daws, from the clan of Abu Hurayrah, who was called Sa'd ibn Malik. The Messenger of Allah, may Allah bless him and grant him peace, said: "This boy, if his life is prolonged, he will not reach old age until the Hour is established." Al-Hasan said: And Anas informed me that the boy was, on that day, of my age.