Sayyiduna Jabir (may Allah be pleased with him) said: On the day of the Conquest of Makkah, Abu Quhafah was brought to the Prophet (peace and blessings be upon him), and his head was as though it were white thughamah grass (completely white). So he (peace and blessings be upon him) said: "Dye it, and avoid black."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 8292