"15 When they had finished breakfast, Jesus said to Simon Peter, “Simon, son of John, do you love me more than these?” He said to him, “Yes, Lord; you know that I love you.” He said to him, “Feed my lambs.” 16 He said to him a second time, “Simon, son of John, do you love me?” He said to him, “Yes, Lord; you know that I love you.” He said to him, “Tend my sheep.” 17 He said to him the third time, “Simon, son of John, do you love me?” Peter was grieved because he said to him the third time, “Do you love me?” and he said to him, “Lord, you know everything; you know that I love you.” Jesus said to him, “Feed my sheep."
John 21:15-17
In the final repetition of the words 'Lovest thou Me?' Jesus used Peter's own word. Clearly he is boring very deeply into the disciple's soul, for now He is calling in question the strength even of this natural love. This has something important to teach us: when the deepest and truest love is at risk, all lesser loves are thereby called in question and weakened. We cannot love as we ought on the human level if spiritual love is at a discount in us.
Our Lord's response to Peter's answers calls for comment. First, it was 'Feed My lambs'; then, 'Tend (the word in the Greek is different) My Sheep'; and finally, 'Feed My sheep'. The commentators suggest there is a progression evident in these words. Those called to the Lord's service are to give spiritual food to the lambs of the flock. In a sense, this is the basic work, feeding those who have come to Him, the new-born babes in Christ (we note in passing the change of metaphor from fishers of men to under-shepherds). In the second response, the words are different. The term used for 'sheep' could well be rendered 'little sheep’ - not that it means 'lambs', for it is a term of affection and endearment. 'Feed' here means 'tend' - giving help, direction, guidance, counsel. Thirdly, the feeding and nurture of those that are of mature spiritual age. And all this dependent on love to Him, for its worthy and proper fulfilment. Indeed, it is not too much to say that the three most important things in Christian discipleship and service may be said to be, love to Jesus, love to Jesus, love to Jesus.