Simon he surnamed Peter (epeqhken onoma twi Simwni Petron). The Greek idiom seems awkward, but it is not. Peter is in apposition with name or onoma (accusative). This surname Jesus gave in addition (epeqhken) to Simon (dative case). Here then is a direct reference to what is told in John 1:42 when Jesus met Simon for the first time. Mark here reflects Peter's own words. Luke ( Luke 6:14 ) simply says "Whom he also surnamed Peter." See Matthew 16:18 for the full explanation of the name Peter, a Rock, Cephas.