45 Immediately he made his disciples get into the boat and go before him to the other side, to Bethsaida, while he dismissed the crowd. 46 And after he had taken leave of them, he went up on the mountain to pray. 47 And when evening came, the boat was out on the sea, and he was alone on the land. 48 And he saw that they were making headway painfully, for the wind was against them. And about the fourth watch of the night he came to them, walking on the sea. He meant to pass by them, 49 but when they saw him walking on the sea they thought it was a ghost, and cried out, 50 for they all saw him and were terrified. But immediately he spoke to them and said, "Take heart; it is I. Do not be afraid." 51 And he got into the boat with them, and the wind ceased. And they were utterly astounded, 52 for they did not understand about the loaves, but their hearts were hardened.
Mark 6:45–52 (ESV)