1 Peter 5:13

She that is in Babylon, elect together with you (h en Babulwni suneklekth). Either actual Babylon or, as most likely, mystical Babylon (Rome) as in the Apocalypse. If Peter is in Rome about A.D. 65, there is every reason why he should not make that fact plain to the world at large and least of all to Nero. It is also uncertain whether h suneklekth (found here alone), "the co-elect woman," means Peter's wife ( 1 Corinthians 9:5 ) or the church in "Babylon." The natural way to take it is for Peter's wife. Cf. eklekth kuriai in 2 John 1:1 (also verse 2 John 1:13 ). Mark my son (Marko o uio mou). So this fact agrees with the numerous statements by the early Christian writers that Mark, after leaving Barnabas, became Peter's "interpreter" and under his influence wrote his Gospel. We know that Mark was with Paul in Rome some years before this time ( Colossians 4:10 ).