Leviticus 25:44-46

Property in foreign slaves is here distinctly permitted. It was a patriarchal custom Genesis 17:12. Such slaves might be captives taken in war (Numbers 31:6 following; Deuteronomy 20:14), or those consigned to slavery for their crimes, or those purchased of foreign slave-dealers. The price of a slave is supposed to have varied from thirty to fifty shekels. See Leviticus 27:3, note; Exodus 21:32, note; Zechariah 11:12, note; Matthew 26:15, note. It was the object of Moses, not at once to do away with slavery, but to discourage and to mitigate it. The Law would not suffer it to be forgotten that the slave was a man, and protected him in every way that was possible at the time against the injustice or cruelty of his master. See the notes at Exodus 21.

Leviticus 25:46

Your bondmen forever - i. e. they were not necessarily to be released in the sabbatical year nor at the Jubilee.