“And he said, Come. And when Peter was come down out of the ship, he walked on the water, to go to Jesus.”
King James Version (KJV)
14:30 He was afraid - Though he had been used to the sea, and was a skilful swimmer. But so it frequently is. When grace begins to act, the natural courage and strength are withdrawn.
Mt 14:29 And he said, Come. I suppose the Lord bade Peter to come in order to teach him a lesson.