Sayyiduna Uthman bin Affan (may Allah be pleased with him) said: "Whoever gives a gift to his young child who has not yet reached the age of taking possession, and announces it and appoints witnesses to it, then it is valid, and his father is its guardian."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الهبات / 11952