It is not permitted for a man to die his beard black because of the reports which command us to avoid that and forbid us to do it. Abu Dawood reported from Jaabir ibn ‘Abd-Allaah who said: “Abu Quhaafah was brought on the day of the Conquest of Makkah, and his head and beard were like thughaamah (a plant whose leaves and flowers are intensely white) because they were so white. The Messenger of Allaah (peace and blessings of Allaah be upon him) said: ‘Change this white hair, but avoid black.’”(Reported by Muslim, al-Nisaa’i and Ibn Maajah). Ahmad, Abu Dawood and al-Nisaa’i reported from Ibn ‘Abbaas (may Allaah be pleased with him) who said: “The Messenger of Allaah (peace and blessings of Allaah be upon him) said: ‘There will be a people at the end of time who will dye their hair black like the crops of pigeons; they will not even smell the fragrance of Paradise.’” But it is encouraged to change grey or white hair by dyeing it any other colour except black, because of the hadeeth of Jaabir quoted above.
It is permitted to dye the hair with henna or any other substance that will give it a reddish or yellowish colour, because it is reported that the Prophet (peace and blessings of Allaah be upon him) used to dye his hair with yellow. Muslim reported that Abu Bakr dyed his hair with henna and katam and that ‘Umar used to dye his hair with henna. The Prophet (peace and blessings of Allaah be upon him) also said, “The best things with which you can change this grey hair are henna and katam.”