Acts 2:18
Yes, and I will pour out my Holy Spirit on my male and female [spiritual] slaves in those days so that they will speak out in prophecies.
Acts 21:10
As we waited there for a number of days, a certain prophet named Agabus came down from Judea.
1 Corinthians 7:21-22
Were you a slave when you were called? It should not matter to you [i.e., if you still are]. But if, indeed, you can become a free person, then use that freedom instead [i.e., for serving God].
Galatians 3:28
[In this relationship] there is to be no [distinction between] Jews or Greeks [i.e., Gentiles], slaves or free persons, men or women; for all of you are united into one [body] because of your relationship with Christ Jesus.
Colossians 3:11
[In this state] there cannot be [such distinctions as] Greek [i.e., Gentile] and Jew; circumcised people and non-circumcised people; barbarian and Scythian [Note: These last two words refer to foreigners whose language was unintelligible and who were uncivilized heathens], or slave and free person; but Christ is all [that is important] and [He is] in all [of His people].