The first boy to embrace Islam was Ali ibn Abu Talib (may Allah be pleased with him). He was ten years old at the time. Ali is the cousin of the Prophet on his father’s side. He used to live with the Prophet (peace be upon him) before Islam in order for the Prophet to take care of him. This was a way of helping Abu Talib and thanking him for his good care of the Prophet when the Prophet was young [Understanding the Companions in depth: the life of Ali ibn Abu Talib].