Riyad as-Salihin 1637

On the day of the Conquest of Makkah, Abu Quhāfah, father of Abu Bakr As-Siddīq, was brought to the Prophet (may Allah's peace and blessings be upon him) and his head and beard were as white as an intensely white plant called Thaghāmah. When the Prophet (may Allah's peace and blessings be upon him) saw him, he said: “Change this and avoid black.”

He ordered that his white hair be dyed with anything other than black, because black makes an old person look younger, and this is a challenge to the natural constitution that Allah gives to man. Red, yellow, and henna mixed with katam-dye are fine to use, so long as black is excluded. If the synthesized dye is something between red and black, it is fine.

In a Hadīth by Anas (may Allah be pleased with him), Abu Bakr and ‘Umar (may Allah be pleased with him) dyed their hair with henna and katam-dye.