Musnad Ahmad 1034:90

Aswad ibn Amir narrated to us, Isra'il narrated to us, from Ibn Abi al-Safar, from al-Sha'bi, from Hudhayfah, who said: I came to the Prophet, peace and blessings of Allah be upon him, and I prayed with him the Dhuhr, the Asr, the Maghrib, and the Isha prayers. Then I followed him while he intended to enter some of his chambers. He stood, and I was behind him, as if he were speaking to someone. He said: Then he said, "Who is this?" I said, "Hudhayfah." He said, "Do you know who was with me?" I said, "No." He said, "Indeed, Gabriel came to give me glad tidings that al-Hasan and al-Husayn are the masters of the youth of the people of Paradise." Hudhayfah said: So he asked for forgiveness for me and for my mother. He said, "May Allah forgive you, O Hudhayfah, and your mother."