Musannaf Ibn Abi Shayba 16:41

Abu Bakr narrated to us, he said: Uthman ibn Matar narrated to us, from Sa'id, who said: Qatadah was asked, "How is the *aqiqah* slaughtered?" He said: "He faces the *qiblah* with it, then places the blade upon its throat, then says: 'O Allah, from You and for You, the *aqiqah* of so-and-so. In the name of Allah, Allah is the Greatest,' then he slaughters it."