John 3:22

Jesus’ conversation with Nicodemus evidently happened in Jerusalem (John 2:23). Jerusalem was within Judea. After that conversation, Jesus went out into the Judean countryside. Jesus had not yet commissioned the Twelve. That commissioning happened after John the Baptist’s imprisonment (Mark 1:14). The disciples who accompanied Jesus may not have been the Twelve, but they were His followers and they could have included all or some of the Twelve. This is the only record in the Gospels that Jesus engaged in a baptizing ministry similar to John the Baptist’s. It was undoubtedly baptism expressing repentance rather than "Christian baptism." The writer later explained that Jesus did not do the baptizing Himself, but His disciples did (John 4:2). Jesus was also spending time with these disciples undoubtedly to help them understand and appreciate who He really was.