Imam Malik (may Allah have mercy on him) narrates from Yahya bin Sa'id (may Allah have mercy on him) that the aqiqah was performed on behalf of the two sons of Sayyiduna Ali bin Abi Talib (may Allah be pleased with him), Hasan and Husayn (may Allah be pleased with them both).
It has also been said that it is from Rabi'ah from Anas, but that is not preserved (mahfuz).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19270