Matthew 14:31

And immediately Jesus stretched forth his hand
The Syriac reads it, (htevrbw) , "and in that very moment"; for his case requires immediate assistance, and Christ readily gave it; he reached out his hand at once, being just by him,

and caught him;
as he was sinking to the bottom, and lifted him up, and set him on his feet upon the water, and enabled him to walk with him to the ship; but not without reproving him for the weakness of his faith,

and said unto him, O thou of little faith:
he does not say, O thou unbeliever! or, O thou who hast no faith! for some faith he had, though but small; of this phrase, (See Gill on Matthew 6:30).

Wherefore didst thou doubt?
waver, fluctuate, or wast divided between faith and fear. He was worthy of reproof, since he had had the order of Christ to come to him upon the water; and an experience of his power in supporting him thus far; and was now so near unto him, that he had no room to doubt, whether it was he or not, nor of his power to preserve him.