{Then after three years} (epeita meta tria et(885c)). A round
number to cover the period from his departure from Jerusalem for
Damascus to his return to Jerusalem. This stay in Damascus was an
important episode in Paul's theological readjustment to his new
experience. {To visit Cephas} (histor(8873)ai K(8870)h(836e)). First aorist
infinitive of histore(935c), old verb (from hist(9372), one who knows
by inquiry), to gain knowledge by visiting. Only here in N.T. If
we turn to  Ac 9:26-30 , we shall see that the visit of two weeks
to Peter came after Barnabas endorsed Paul to the suspicious
disciples in Jerusalem and probably while he was preaching in the
city. It was a delightful experience, but Peter did not start
Paul upon his apostleship. He visited him as an equal. Peter no
doubt had much to say to Paul.