Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) narrates: Sayyiduna Hasan (may Allah be pleased with him) came to the Prophet (peace and blessings be upon him) while the Prophet (peace and blessings be upon him) was in prostration. Sayyiduna Hasan (may Allah be pleased with him) (who was a child) climbed onto the back of the Prophet (peace and blessings be upon him). The Prophet (peace and blessings be upon him) held him with his hand until he stood up. When he went into bowing (ruku'), he again climbed onto his back. When the Prophet (peace and blessings be upon him) stood up, he let him go, and he went away.
Al-Bazzar recorded it, and there is disagreement about its narrators.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب المناقب / 15033