Sayyiduna Ali (may Allah be pleased with him) once submitted in the court of the Messenger, "O Messenger of Allah! Please tell me, if after you a boy is born to me, can I name him after you and give him your kunyah?" He replied, "Yes!" This was a permission from the Prophet (peace and blessings be upon him) for Sayyiduna Ali (may Allah be pleased with him).
Hadith Referenceمسند احمد / مسند الخلفاء الراشدين / 730