Sayyiduna Salman bin Amir (may Allah be pleased with him) narrates a marfu' hadith that the Prophet (peace and blessings be upon him) said: "A child is held in pledge for his aqiqah; the impurity is to be removed from him, and on the seventh day blood is to be shed on his behalf."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19292