John Calvin on John 21:12-13

12. And not one of his disciples dared to ask him. It may be inquired, What hindered them? Was it shame arising from reverence, or was it any thing else? But if Christ saw that they were in a state of uncertainty, he ought to remove their doubt, as he had done on many other occasions. I reply, there was no other reason for shame, but because they were not sufficiently certain that he was the Christ; for it is not usual with us to inquire about matters that are doubtful and obscure. The Evangelist, therefore, means that the disciples did not ask Christ, because they were afraid of doing him wrong; so plain and manifest were the signs by which he had made himself known to them.