Leviticus 25:40-44

He shall be with you as a hired worker, as if he were a foreign resident; he shall serve with you up to the year of jubilee.

He shall then leave you, he and his sons with him, and shall go back to his family, so that he may return to the property of his forefathers.

For they are My servants whom I brought out from the land of Egypt; they are not to be sold in a slave sale.

You shall not rule over him with severity, but are to revere your God.

As for your male and female slaves whom you may have—you may acquire male and female slaves from the pagan nations that are around you.