Ikrimah (may Allah have mercy on him) narrates from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that the Messenger of Allah (peace and blessings be upon him) slaughtered one ram each as aqiqah on behalf of Hasan and Husayn (may Allah be pleased with them both).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19283
Nafi' narrates from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that whenever any of his children asked him for an aqiqah, he would give it to him, and he would perform the aqiqah for his children, male and female alike, with one goat each.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19284
Hisham bin Urwah narrates from his father, Urwah bin al-Zubayr (may Allah have mercy on him), that he used to perform the aqiqah for his sons and daughters with one goat each.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19285