Sayyiduna Ali bin Abi Talib (may Allah be pleased with him) says: As for Hasan, Husayn and Muhsin, it was the Prophet (peace and blessings be upon him) who named them. He had their aqiqahs performed, had their heads shaved and gave in charity the equivalent of the weight of their (hair). The Prophet (peace and blessings be upon him) gave instructions concerning them, so their umbilical cords were cut and they were circumcised.
Al-Tabarani recorded it in al-Kabir; its chain contains Atiyyah al-Awfi, who is da'if (weak), though he has also been declared trustworthy.