Leviticus 25:46

You can will them to your children as inherited property and can make them slaves for life, but you must not rule over your fellow Israelites ruthlessly.

(New International Version)

'You may even bequeath them to your sons after you, to receive as a possession; you can use them as permanent slaves. But in respect to your countrymen, the sons of Israel, you shall not rule with severity over one another.

(New American Standard Bible)

And ye shall take them as an inheritance for your children after you, to inherit them for a possession; they shall be your bondmen for ever: but over your brethren the children of Israel, ye shall not rule one over another with rigour.

(King James Version)