1 Corinthians 7:18-20 (KJV)
18 Is any man called being circumcised? let him not become uncircumcised. Is any called in uncircumcision? let him not be circumcised.
19 Circumcision is nothing, and uncircumcision is nothing, but the keeping of the commandments of God.
20 Let every man abide in the same calling wherein he was called.