Leviticus 25:42
Since they're my servants whom I've brought out of the land of Egypt, they are not to be sold as slaves.
Leviticus 25:55
because the Israelis are my servants. They're my servants, since I brought them out of the land of Egypt. I am the LORD your God."
Romans 6:22
But now that you have been freed from sin and have become God's slaves, the benefit you reap is sanctification, and the result is eternal life.
1 Corinthians 7:21-23
Were you a slave when you were called? Do not let that bother you. Of course, if you have a chance to become free, take advantage of the opportunity.