Is it permissible to dye the beard or hair black, even with katam, and what is katam, and did some of the Companions use it?

Dyeing gray hair is a Sunnah using henna and katam. This differs from dyeing with black dye, which is forbidden in Sharia, based on the hadith: "There will be people who dye their hair black like the crops of pigeons; they will not smell the fragrance of Paradise." Katam is a plant in Yemen that produces a black dye with a reddish tint. When mixed with henna, it gives a color between black and red. The Prophet (peace be upon him) and his Companions dyed their hair with it.