A.T. Robertson Commentary Mark 3:16

"and Simon he surnamed Peter;" — Mark 3:16 (ASV)

Simon he surnamed Peter (επεθηκεν ονομα τω Σιμων Πετρον). The Greek idiom seems awkward, but it is not. Peter is in apposition with name or ονομα (accusative). This surname Jesus gave in addition (επεθηκεν) to Simon (dative case). Here then is a direct reference to what is told in Joh 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 Mt 16:18 for the full explanation of the name Peter, a Rock, Cephas.