An “eved Ivri” – literally “Hebrew slave” – was a Jew who sold himself into indentured servitude because of financial straits. One was not permitted to give him degrading tasks, like carrying the master’s clothes to the bath house. Not only that, the eved Ivri was to be served the same food the master himself eats and sleep on a bed of the same quality as the master's. Because of the stringent restrictions on what one do with an eved Ivri, the Talmud says (Kiddushin 22a) that one who acquires an eved Ivri actually acquires a master for himself. (That notwithstanding, the eved Ivri is required to show deference to his master.)

The root of this mitzvah is that it is unseemly to mistreat another person. One who purchases an eved Ivri must realize that difficult circumstances drove this person to indenture himself. Such tragedies could likewise befall the master. Therefore, it behooves him to treat the eved Ivri as he would want to be treated if the shoe were on the other foot.

This mitzvah applied to both men and women in Israel at a time when the Jubilee year was observed. It is discussed in the Talmud in tractate Kiddushin on page 22a. It is codified in the Mishneh Torah in the first chapter of Hilchos Avadim and is #257 of the 365 negative mitzvos in the Rambam’s Sefer HaMitzvos.