Here is the story: After feeding the 5,000 the next stop for Jesus and the disciples was to go across the sea to Capernaum. The disciples climbed aboard, but Jesus stayed back for a time of prayer. By the time Jesus had finished praying the disciples had started the journey, leaving Jesus behind. So, Jesus walks out on the water (because He can) and calmly greets the disciples who are terrified. They think Jesus is a ghost, but Jesus reassures them He is not a ghost, that it is Him. However, that answer wasn't good enough for Peter and he exclaims, "Lord, if it is you, command me to come to you on the water." Jesus doesn't put up a fight or make a scene, He simply does what He has been doing to every person he has spoken with: He invites them.