It is narrated from Sayyiduna Anas (may Allah be pleased with him) that a Jewish boy used to serve the Prophet (peace and blessings be upon him). He fell ill, so the Prophet (peace and blessings be upon him) went to visit him. The Messenger of Allah (peace and blessings be upon him) sat by his head. The boy looked at his father, and he said: "Obey Abu al-Qasim." So he became Muslim. When the Messenger of Allah (peace and blessings be upon him) came out, he was saying: "All praise is for Allah who has saved him from the Fire through me."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب اللقطة / 12157