'Slave' in the Bible

Were you called while a slave? It should not be a concern to you. But if you can become free, by all means take the opportunity.

For he who is called by the Lord as a slave is the Lord’s freedman. Likewise he who is called as a free man is Christ’s slave.

Although I am a free man and not anyone’s slave, I have made myself a slave to everyone, in order to win more people.