Majma al-Zawaid — Hadith 15081

Sayyiduna Salman al-Farisi (may Allah be pleased with him) narrates: We were gathered around the Prophet (peace and blessings be upon him). Meanwhile Sayyidah Umm Ayman came and said: "O Messenger of Allah! Hasan and Husayn are lost." The narrator says: This was when the day had risen high. The Prophet (peace and blessings be upon him) said: "Get up, all of you, and search for my two sons." So each man set off in the direction in front of him. The narrator says: I set off in the direction the Prophet (peace and blessings be upon him) took. After a little while, the Prophet (peace and blessings be upon him) reached the foot of a mountain, and there were Sayyiduna Hasan (may Allah be pleased with him) and Sayyiduna Husayn (may Allah be pleased with him), clinging to each other. And there was a serpent standing on its tail, with something like sparks of fire coming out of its mouth. The Prophet (peace and blessings be upon him) hurried towards it. It turned, looked towards the Prophet (peace and blessings be upon him) and said something, then turned away and went into its hole. Then the Prophet (peace and blessings be upon him) came to the two boys and separated them from each other. He passed his hand over their faces and said: "May my father and mother be sacrificed for you! How honoured you both are with Allah Almighty!" Then he seated one of them on his right shoulder and the other on his left shoulder. I said: "Glad tidings to you both! How excellent your mount is!" The Prophet (peace and blessings be upon him) said: "And how excellent these two riders are, and their father is better than both of them."
Al-Tabarani recorded it. Its chain contains a narrator, Ahmad bin Rushd al-Hilali, and he is da'if (weak).