It is narrated from Sayyiduna Samurah (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "Every newborn is held in pledge for his aqiqah; (an animal) is to be slaughtered on his behalf on the seventh day, he is to be given a name, and his head is to be shaved."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6901