Ruling on dyeing
    the hair and beard black
Question

                Is it permitted to dye the beard black?
Praise be to Allah.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.”