1 Corinthians 7:21

7:21 Were you called as a slave? Do not worry about it. But if indeed you are able to be free, make the most of the opportunity.

1 Corinthians 9:19

9:19 For since I am free from all I can make myself a slave to all, in order to gain even more people.

1 Corinthians 9:27

9:27 Instead I subdue my body and make it my slave, so that after preaching to others I myself will not be disqualified.