Charles Ellicott Commentary Mark 6:46-51

"And after he had taken leave of them, he departed into the mountain to pray. And when even was come, the boat was in the midst of the sea, and he alone on the land. And seeing them distressed in rowing, for the wind was contrary unto them, about the fourth watch of the night he cometh unto them, walking on the sea; and he would have passed by them: but they, when they saw him walking on the sea, supposed that it was a ghost, and cried out; for they all saw him, and were troubled. But he straightway spake with them, and saith unto them, Be of good cheer: it is I; be not afraid. And he went up unto them into the boat; and the wind ceased: and they were sore amazed in themselves;" — Mark 6:46-51 (ASV)

And when he had sent them away.—See Notes on Matthew 14:22-33.