´It was narrated from Abu Dharr that:` The Prophet [SAW] said: "The best things with which you can change gray hair are Henna and Katam."
Explanation & Benefits
Hafiz Muhammad Ameen
(1) From this blessed hadith, it is understood that the dye of henna (mehndi) and katam (wasmah) is the best and most virtuous. Furthermore, dyeing is not limited to only these two things (henna and katam); rather, there are also many other types of dyes. Caution is only with regard to using jet-black dye, and this prohibition is equally applicable to both men and women.
(2) This blessed hadith also indicates the permissibility of using dyes made from mixed substances.
(3) By mixing both henna (mehndi) and katam (wasmah), the color does not remain purely black; rather, it becomes tinged with redness.
Source: Sunan Nasa'i: Translation and Benefits by Shaykh Hafiz Muhammad Amin Hafizullah, Page: 5080