I have heard that it is wrong for a muslim woman to dye her hair black.Is this true and why is it wrong to do so?

In the name of Allah, Most Gracious, Most Merciful

Assalaamu `alaykum waRahmatullahi Wabarakatoh

Pure black dye is not permissible. Rasulullah صلى الله عليه وسلم said, "There will be people who will come later (in my Ummah) and apply black dye. They will not even smell the fragrance of paradise." (Abu Daawood).

To dye the hair any other colour besides black e.g. Mehndi or Katm (type of grass) is permissible. This was the practice of Rasulullah (صلى الله عليه وسلم) and the Sahaaba (Radhiyallaahu Ánhum). (Jawahirul Fiqh vol2 pg421)

Al-Mahmood Vol.1 pg.22

And Allah knows best

Wassalam

Mufti Ebrahim Desai
Darul Iftaa