And when the disciples saw him walking on the sea, they were troubled, saying, It is a {d} spirit; and they cried out for fear.

(d) A spirit, as it is taken here, is that which a man imagines to himself vainly in his mind, persuading himself that he sees something when he sees nothing.

People's New Testament

14:26 A spirit. An apparition, an unreal appearance of a real person. The Greek word phantasma is not that unusually rendered spirit. He would appear to them at first like a dark, moving speck upon the waters, then as a human figure; but in the dark, tempestuous sky, and not dreaming that it could be their Lord, they take it for a spirit, pneuma (Lu 24:37).

Cried out. In fright.

Matthew Henry's Concise Commentary

14:22-33 Those are not Christ's followers who cannot enjoy being alone with God and their own hearts. It is good, upon special occasions, and when we find our hearts enlarged, to continue long in secret prayer, and in pouring out our hearts before the Lord. It is no new thing for Christ's disciples to meet with storms in the way of duty, but he thereby shows himself with the more grace to them and for them. He can take what way he pleases to save his people. But even appearances of deliverance sometimes occasion trouble and perplexity to God's people, from mistakes about Christ. Nothing ought to affright those that have Christ near them, and know he is theirs; not death itself. Peter walked upon the water, not for diversion or to boast of it, but to go to Jesus; and in that he was thus wonderfully borne up. Special supports are promised, and are to be expected, but only in spiritual pursuits; nor can we ever come to Jesus, unless we are upheld by his power. Christ bade Peter come, not only that he might walk upon the water, and so know his Lord's power, but that he might know his own weakness. And the Lord often lets his servants have their choice, to humble and prove them, and to show the greatness of his power and grace. When we look off from Christ, and look at the greatness of opposing difficulties, we shall begin to fall; but when we call to him, he will stretch out his arm, and save us. Christ is the great Saviour; those who would be saved, must come to him, and cry to him, for salvation; we are never brought to this, till we find ourselves sinking: the sense of need drives us to him. He rebuked Peter. Could we but believe more, we should suffer less. The weakness of faith, and the prevailing of our doubts, displease our Lord Jesus, for there is no good reason why Christ's disciples should be of a doubtful mind. Even in a stormy day he is to them a very present help. None but the world's Creator could multiply the loaves, none but its Governor could tread upon the waters of the sea: the disciples yield to the evidence, and confess their faith. They were suitably affected, and worshipped Christ. He that comes to God, must believe; and he that believes in God, will come, Heb 11:6.