For he who is called in the Lord while a slave is the Lord's freedman. Likewise he who is called while free is Christ's slave.
1 Corinthians 7:22
Surrounding context
7:21 Were you called while a slave? Do not be concerned about it; but if you can be made free, rather use it.
7:22 For he who is called in the Lord while a slave is the Lord's freedman. Likewise he who is called while free is Christ's slave.
7:23 You were bought at a price; do not become slaves of men.