Someone asked Hazrat Jabir (may Allah be pleased with him) about the white hair of the Prophet (peace and blessings be upon him), so he replied that there were only a few white hairs in the hair of the Prophet (peace and blessings be upon him). When he applied oil, the whiteness of the hair was not apparent.
Hadith Referenceمسند احمد / أول مسند البصريين / 20840