Abrahamic religions often refer to them as the first monotheists. In my opinion they predate Zoroastrianism too. The only mention that Islamic texts do make is when referring to them as one of the People of Paradise - the Sabeans (alternative name for Mandaeans) https://twitter.com/Iraq_Tweets/status/1300502406405304320

however many contest the theory that they are the one and the same with the fact that Sabaeans/Sabeans could be those related to Queen Sheba (Saba). That it may not have been interchangeable at all

They pray three times a day, in Aramic. They are forbidden to mourn the dead and fast 36 days in a year. One can only become a Mandaean-Sabaean through birth; there is no baptism or conversion like other Abrahamic religions

They wear white to signify purity. Their symbol resembles the Christian cross but unlike the cross; it is half covered with a cloth. The reason being that they do not consider Jesus to be the son of God. God is one and indivisible for them.

The Mandaeans are a peaceful community, but have faced displacement and ostracization for their faith. Because they don't seem to fit the mold of the Abrahamic teachings and neither do they completely relate to other religions.

The original monotheists. The first of the firsts. Possibly the "Hanifs" (monotheists that existed in Pre-Islamic Arabia). As a community that is on the brink of disappearing forever; the very little of mention of them in religious literature is astounding.

This was not even supposed to be a proper thread but it all came pouring out

I attribute most of this knowledge to my Islamic culture professor in uni. Bless Dr Kobaisi