15:12 If your fellow Hebrew – whether male or female – is sold to you and serves you for six years, then in the seventh year you must let that servant go free.
15:13 If you set them free, you must not send them away empty-handed.
Deuteronomy 15:17
15:17 you shall take an awl and pierce a hole through his ear to the door. Then he will become your servant permanently (this applies to your female servant as well).