Musnad Abu Ya'la al-Mawsili 150:17

Ishaq narrated to us, Abd al-Majid ibn Abd al-Aziz ibn Abi Rawwad narrated to us, from Ibn Jurayj, from Yahya ibn Sa’id, from Amrah, from Aisha, who said: "Two equivalent sheep are sacrificed for a boy, and one sheep for a girl." Aisha said: "The Messenger of Allah (peace and blessings of Allah be upon him) performed the *aqiqah* for al-Hasan and al-Husayn with two sheep each on the seventh day, and he ordered that the harm be removed from his head, and he said: 'Slaughter in his name and say: In the name of Allah, Allah is the Greatest. O Allah, from You and to You, this is the *aqiqah* of so-and-so.'" She said: "In the pre-Islamic era, a piece of cotton would be taken and placed in the blood of the *aqiqah*, then it would be placed on his head. So the Messenger of Allah (peace and blessings of Allah be upon him) ordered them to place *khuluq* (saffron-based perfume) in place of the blood."