mark 6:50 For they all saw him, and were troubled. And immediately he talked with them, and saith unto them, Be of good cheer: it is I; be not afraid. - Free Bible Online

      50. For they all saw him, and were troubled. And immediately he talked with them, and saith unto them, Be of good cheer: It is I; be not afraid--There is something in these two little words--given by Matthew, Mark and John (Mt 14:27; Mr 6:50; Joh 6:20) --"It is I," which from the mouth that spake it and the circumstances in which it was uttered, passes the power of language to express. Here were they in the midst of a raging sea, their little bark the sport of the elements, and with just enough of light to descry an object on the waters which only aggravated their fears. But Jesus deems it enough to dispel all apprehension to let them know that He was there. From other lips that "I am" would have merely meant that the person speaking was such a one and not another person. That, surely, would have done little to calm the fears of men expecting every minute, it may be, to go to the bottom. But spoken by One who at that moment was "treading upon the waves of the sea," and was about to hush the raging elements with His word, what was it but the Voice which cried of old in the ears of Israel, even from the days of Moses, "I AM"; "I, EVEN I, AM HE!" Compare Joh 18:5, 6; 8:58. Now, that Word is "made flesh, and dwells among us," uttering itself from beside us in dear familiar tones--"It is the Voice of my Beloved!" How far was this apprehended by these frightened disciples? There was one, we know, in the boat who outstripped all the rest in susceptibility to such sublime appeals. It was not the deep-toned writer of the Fourth Gospel, who, though he lived to soar beyond all the apostles, was as yet too young for prominence, and all unripe. It was Simon Barjonas. Here follows a very remarkable and instructive episode, recorded by Matthew alone:

Peter Ventures to Walk upon the Sea (Mt 14:28-32).

Mt 14:28:
      And Peter answered Him, and said, Lord, If it be Thou, bid me come unto Thee on the water--not "let me," but "give me the word of command"--"command," or "order me to come unto Thee upon the waters."

Mt 14:29:
      And He said, Come--Sublime word, issuing from One conscious of power over the raging element, to bid it serve both Himself and whomsoever else He pleased!
      And when Peter was come down out of the ship, he walked upon the water--"waters."
      to come to Jesus--"It was a bold spirit," says BISHOP HALL, "that could wish it; more bold that could act it--not fearing either the softness or the roughness of that uncouth passage."

Mt 14:30:
      But when he saw the wind boisterous, he was afraid: and beginning to sink, he cried, saying, Lord, save me--The wind was as boisterous before, but Peter "saw" it not, seeing only the power of Christ, in the lively exercise of faith. Now he "sees" the fury of the elements, and immediately the power of Christ to bear him up fades before his view, and this makes him "afraid"--as how could he be otherwise, without any felt power to keep him up? He then "begins to sink"; and finally, conscious that his experiment had failed, he casts himself, in a sort of desperate confidence, upon his "Lord" for deliverance!

Mt 14:31:
      And immediately Jesus stretched forth His hand, and caught him, and said unto him, O thou of little faith, wherefore didst thou doubt?--This rebuke was not administered while Peter was sinking, nor till Christ had him by the hand: first reinvigorating his faith, and then with it enabling him again to walk upon the crested wave. Useless else had been this loving reproof, which owns the faith that had ventured on the deep upon the bare word of Christ, but asks why that distrust which so quickly marred it.

Mt 14:32:
      And when they--Jesus and Peter.
      were come into the ship, the wind ceased.

JFB.