Salman was the very educated priest Magi, who was against Persian Cast system only.

As slave, he wrote Qur'an by copying Bible, old Testament and Zoroastrian books.

The Brotherhood and equality was his idea, One God (the same as Persians to Unite everyone), 5 times prayers, the same as Persians, as well as Charity (the same as Persians), as well as many other Good things in Qur'an. He wrote Qur'an so well, they thought Allah has written it. Muhammad Added the Hadith and Moon Worship/ Hajj