Matthew 14:29-31

and he said, `Come;' and having gone down from the boat, Peter walked upon the waters to come unto Jesus,

but seeing the wind vehement, he was afraid, and having begun to sink, he cried out, saying, `Sir, save me.'

And immediately Jesus, having stretched forth the hand, laid hold of him, and saith to him, `Little faith! for what didst thou waver?'