When therefore they had rowed about twenty-five or thirty stadia,{25 to 30 stadia is about 5 to 6 kilometers or about 3 to 4 miles} they saw Jesus walking on the sea, and drawing near to the boat; and they were afraid.
But there are some of you that believe not. For Jesus knew from the beginning who they were that believed not, and who would betray him. And he said, Therefore I said unto you, that no man can come unto me, except it were given unto him of my Father ( John 6:64-65 ).