1 Corinthians 7:20-23

Each one should remain in the condition in which he was [when he was] called. Were you a slave when you were called? Do not worry about that [since your status as a believer is equal to that of a freeborn believer]; but if you are able to gain your freedom, do that. For he who was a slave when he was called in the Lord is a freedman of the Lord, likewise he who was free when he was called is a slave of Christ. You were bought with a price [a precious price paid by Christ]; do not become slaves to men [but to Christ].