Sabian (n.)

an adherent of a religious sect mentioned thrice in the Qu'ran (in which they are classified with Christians, and Jews as "true believers" worth of toleration by Muslims), 1610s, from Arabic, of uncertain origin. As an adjective from 1748.

Perhaps the reference is to a Gnostic sect akin to the later Mandæans (if the word derives, as some think it does, from Arabic ch'bae "to baptize," Aramaic tzebha "he dipped, dyed"); but it has the appearance of derivation from the Semitic root of Hebrew tzabha "host" (see Sabaoth), and as the Sabians were thought in the Middle Ages to have been star-worshippers, it was interpreted as referring to the "host of heaven." Related: Sabaism.