john 21:15 So when they had dined, Jesus saith to Simon Peter, Simon, son of Jonas, lovest thou me more than these? He saith unto him, Yea, Lord; thou knowest that I love thee. He saith unto him, Feed my lambs. - Free Bible Online

      15-17. when they had dined, Jesus saith--Silence appears to have reigned during the meal; unbroken on His part, that by their mute observation of Him they might have their assurance of His identity the more confirmed; and on theirs, from reverential shrinking to speak till He did.
      Simon, son of Jonas, lovest thou me more than these?--referring lovingly to those sad words of Peter, shortly before denying his Lord, "Though all men shall be offended because of Thee, yet will I never be offended" (Mt 26:33), and intending by this allusion to bring the whole scene vividly before his mind and put him to shame.
      Yea, Lord; thou knowest that I love thee--He adds not, "more than these," but prefixes a touching appeal to the Saviour's own omniscience for the truth of his protestation, which makes it a totally different kind of speech from his former.
      He saith unto him, Feed my lambs--It is surely wrong to view this term as a mere diminutive of affection, and as meaning the same thing as "the sheep" [WEBSTER and WILKINSON]. It is much more according to usage to understand by the "lambs," young and tender disciples, whether in age or Christian standing (Isa 40:11; 1Jo 2:12, 13), and by the "sheep" the more mature. Shall we say (with many) that Peter was here reinstated in office? Not exactly, since he was not actually excluded from it. But after such conduct as his, the deep wound which the honor of Christ had received, the stain brought on his office, the damage done to his high standing among his brethren, and even his own comfort, in prospect of the great work before him, required some such renewal of his call and re-establishment of his position as this.

JFB.