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 you shall let go every man his brother who is a Hebrew, who has been sold to you, and has served you six years, you shall let him go free from you: but your fathers didn't listen to me, neither inclined their ear.
Leviticus 25:39-41
"'If your brother has grown poor among you, and sells himself to you; you shall not make him to serve as a slave.
Exodus 21:2-6
"If you buy a Hebrew servant, he shall serve six years and in the seventh he shall go out free without paying anything.
Deuteronomy 15:1
At the end of every seven years you shall make a release.
John 8:35-36
A bondservant doesn't live in the house forever. A son remains forever.