Leviticus 25:44-46 King James Version (KJV)
44 Both thy bondmen, and thy bondmaids, which thou shalt have, shall be of the heathen that are round about you; of them shall ye buy bondmen and bondmaids.
45 Moreover of the children of the strangers that do sojourn among you, of them shall ye buy, and of their families that are with you, which they begat in your land: and they shall be your possession.
46 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.
Leviticus 25:44-46 New International Version (NIV)
44 “‘Your male and female slaves are to come from the nations around you; from them you may buy slaves. 45 You may also buy some of the temporary residents living among you and members of their clans born in your country, and they will become your property. 46 You can bequeath them to your children as inherited property and can make them slaves for life, but you must not rule over your fellow Israelites ruthlessly.