Gálatas 2:11

Peter had shaken hands with Paul in Jerusalem (Galatians 2:9). However when Peter came to Antioch (of Syria) Paul opposed him. Luke did not record this later event in Acts, and we cannot date it exactly. It may have happened shortly after Paul and Barnabas returned from Jerusalem to Antioch or, less likely, after the Jerusalem Council (cf. Acts 15:30). I think the second possibility is less likely because I believe Paul wrote Galatians before the Jerusalem Council, as explained above.