Leviticus 25:44-46

⁴⁴'And thy man-servant and thy handmaid whom thou hast are of the nations who are round about you; of them ye buy man-servant and handmaid,

⁴⁵and also of the sons of the settlers who are sojourning with you, of them ye buy, and of their families who are with you, which they have begotten in your land, and they have been to you for a possession;

⁴⁶and ye have taken them for inheritance to your sons after you, to occupy for a possession; to the age ye lay service upon them, but upon your brethren, the sons of Israel, one with another, thou dost not rule over him with rigour.