Sabaean

As to the religion of the Sabaeans, very little is known about the origins of this religion, though we Bahá’ís are certain of one thing, that the founder of it has been a divinely-sent Messenger. The country where Sabaeanism became widespread and flourished was Chaldea, and Abraham is considered as having been a follower of that Faith.

Shoghi Effendi, The Compilation of Compilations vol. I, p. 20

With reference to your question concerning the Sabaean and Hindu religions: there is nothing in the Teachings that could help us in ascertaining which one of these two Faiths is older. Neither history seems to be able to provide a definite answer to this question. The records concerning the origin of these religions are not sufficiently detailed and reliable to offer any conclusive evidence on this point.

Shoghi Effendi, The Compilation of Compilations vol. I, p. 20