What three religious groups opposed slavery?

I would expect there are more than three. These three could get us started.

ZarathUshtra (circ 4000bce) was opposed to slavery, even to the gods. It was the Magians and Achæmenids who resurrected the gods and enslaved the world in the name of the newly reborn Zoroastrian gods.

Buddhism and Jainism (600 bce), and their youngest brother, Sikhism (15th century ce) oppose slavery for the same reason ZarathUshtra taught against it. One ought to be responsible for one's own enlightenment. And slaves aren't allowed to be responsible for themselves, nor even have their own thoughts.

The Bogomils / Cathar (9th to 12th century ce) gnostics opposed slavery, even teaching trade and self-reliance as the path out of oppression and onto enlightenment.