Joshua 9:19-21

But all the leaders said to the whole congregation, “We have sworn to them by the LORD, the God of Israel, so now we cannot touch them. This [is what] we will do to them: we will let them live, so that the wrath [of God] does not come upon us for [violating] the oath which we have sworn to them.” The leaders said to them, “Let them live [as our slaves].” So they became the cutters and gatherers of firewood and water carriers for the entire congregation, just as the leaders had said of them.