Sayyiduna Ali (may Allah be pleased with him) said: I loved to have the kunyah Abu Harb. So when Sayyiduna al-Hasan was born, I named him Harb. Then the Prophet (peace and blessings be upon him) came and said: "What name have you given?" I said: I have named him Harb. He said: "He is Hasan."
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 2762