Is It Prohibited to Dye Your Hair Black?
Question

I would like to know if Muslims are allowed to dye their hair (not including henna).
Praise be to Allah.Jabir ibn `Abdullah (may Allah be pleased with him) reported that Abu Quhafah was brought on the day of the conquest of Makkah, and his head and beard were white like "thaghamah" (a plant whose flowers and fruit are white). The Messenger of Allah (Peace and Blessings of Allah be upon Him) said: "Change this with something, but avoid black." (Narrated by Muslim, 3962)

Ibn `Abbas (may Allah be pleased with him) said: "The Messenger of Allah (Peace and Blessings of Allah be upon Him) said: `At the end of time there will be people who will dye their hair black like the crops of pigeons. They will never even smell the fragrance of Paradise." (Narrated by Ahmad; see also Sahih Al-Jami`, 8153)

It was also reported from the Prophet (Peace and Blessings of Allah be upon Him) that one should change grey hair, using any colour except black . Abu Dharr (may Allah be pleased with him) reported that the Prophet (Peace and Blessings of Allah be upon Him) said: "The best things with which to change grey hair are henna and ‘katam’ (a plant similar to henna which is used as a dye)." (Narrated by At-Tirmidhi, 1675; he said: This is an authentic Hadith).

Dyeing hair with pure black dye is prohibited because the Prophet (Peace and Blessings of Allah be upon Him) said: "Avoid black," and because of the threat of punishment reported with regard to this matter. This ruling applies to both men and women .

But if the black dye is mixed with another colour, so that it is no longer black, there is nothing wrong with it. (See, Fatwa Islamiyyah, 4/424, Fatawa Al-Mar’ah Al-Muslimah, 2/520)
For more details, please refer to the following answers: 82103 , 6455 , 235954 , 7227 , and 47652 . 
And Allah knows best.