John Gill Commentary John 21:16

"He saith to him again a second time, Simon, [son] of John, lovest thou me? He saith unto him, Yea, Lord; thou knowest that I love thee. He saith unto him, Tend my sheep." — John 21:16 (ASV)

He says to him again the second time
Willing to have the expressions of his love repeated and confirmed;

Simon, son of Jonas, do you love me ?
he leaves out the words, "more than these", though Nonnus expresses them; he saw Peter's heart, and observed the modesty of his answer, and would not urge him any more in that comparative way, only required a repetition of his sincere and hearty love to him:

he says to him, yes, Lord, you know that I love you ;
expressing himself in the same language as before; and it is, as if he should say, Lord, what can I say more? I can say no more than I have done, and by that I abide:

he says to him, feed my sheep ;
both the lost sheep of the house of Israel, and his other sheep among the Gentiles, whom the Father had given him, and he had paid a price for, and must be brought in; these being called, he would have fed with the word and ordinances, with the bread of life, and water of life, not lorded over, and fleeced, and much less worried and destroyed; every instance of care and love shown to these, he takes as a mark of affection and respect to himself.