And when James, Cephas, and John, who seemed to be pillars, perceived the grace that was given unto me, they gave to me and Barnabas the right hand of fellowship; that we should go unto the Gentiles, and they unto the circumcision.
All Commentaries on Galatians 2:9 Go To Galatians 2
Tertullian of Carthage
AD 220
Because Paul had presented himself as an adversary to Him They accordingly even gave him "the right hand of fellowship".
Accordingly, the false brethren who were the spies of their Christian liberty must be thwarted in their efforts to bring it under the yoke of their own Judaism before that Paul discovered whether his labour had been in vain, before that those who preceded him in the apostolate gave him their right hands of fellowship, before that he entered on the office of preaching to the Gentiles, according to their arrangement with him.
Rightly, then, did Peter and James and John give their right hand of fellowship to Paul, and agree on such a division of their work, as that Paul should go to the heathen, and themselves to the circumcision.