Sayyiduna Ali (may Allah be pleased with him) said: "As for Hasan, Husayn and Muhassin, the Messenger of Allah (peace and blessings be upon him) named them, offered the aqiqah on their behalf, had their heads shaved and gave in charity the equivalent of the weight of their hair, and he gave orders concerning them, so their umbilical cords were cut and they were circumcised."
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 2558