John Calvin Commentary John 21:7

"That disciple therefore whom Jesus loved saith unto Peter, It is the Lord. So when Simon Peter heard that it was the Lord, he girt his coat about him (for he was naked), and cast himself into the sea." — John 21:7 (ASV)

Therefore the disciple whom Jesus loved says to Peter. The Evangelist shows, by his example, that it is our duty to raise our hearts to God whenever we succeed in anything beyond our expectation. We ought instantly to remember that this act of kindness has flowed from the favor of Him who is the Author of every blessing.

That holy recognition of the grace of God, which dwelt in the heart of John, also led him to the knowledge of Christ; for he did not perceive Christ with his eyes, but being convinced that the great multitude of fishes had been brought to him by the hand of God, he concluded that it was Christ who had guided his hands.

But, as John precedes Peter in faith, so Peter afterwards excels him in zeal, when he throws himself into the lake, disregarding personal danger. The rest follow in the ship. True, all eventually come to Christ, but Peter is driven by a special zeal compared to the others.

Whether he crossed over to the shore by walking or by swimming, is uncertain; but let us be satisfied with knowing that his act of leaving the ship and going ashore was not the result of folly and rashness, but rather showed that he advanced beyond the others in proportion to his zeal.