Deuteronomy 15:12
If your brother, a Hebrew man or a Hebrew woman, is sold to you and serves you six years, then in the seventh year you shall let him go free from you.
Jeremiah 34:14
At the end of seven years each man should let go his brother, a Hebrew, and who has been sold to him. And when he has served you six years, you shall let him go free from you. But your fathers did not listen to me, nor bow down their ears.
Leviticus 25:39-41
And if your brother who lives beside you has become poor, and is sold to you, you shall not compel him to serve as a bond-servant.
Exodus 21:2-6
If you buy a Hebrew servant, he shall serve six years. And in the seventh he shall go out free for nothing.
Deuteronomy 15:1
At the end of every seven years you shall make a release.
John 8:35-36
And the slave does not abide in the house forever, but the Son abides forever.