Abdul Quddus bin al-Hajjaj al-Khulani عبد القدوس بن الحجاج الخولاني · The Book on Sacrifices

They entered upon Hafsah bint 'Abdur-Rahman to ask her about the 'Aqiqah. She informed them that 'Aishah had informed her, that the Messenger of Allah (ﷺ) ordered them that for a boy, two sheep were sufficient, and for a girl one sheep.