Its in 2nd Peter 1 but read the whole chapter and include it or you lose the context of what Peter is teaching.
1Simeon* Peter, a servant* and apostle of Jesus Christ,
To those who have received a faith as precious as ours through the righteousness of our God and Saviour Jesus Christ:*
2 May grace and peace be yours in abundance in the knowledge of God and of Jesus our Lord.
3 His divine power has given us everything needed for life and godliness, through the knowledge of him who called us by* his own glory and goodness. 4Thus he has given us, through these things, his precious and very great promises, so that through them you may escape from the corruption that is in the world because of lust, and may become participants in the divine nature. 5For this very reason, you must make every effort to support your faith with goodness, and goodness with knowledge, 6and knowledge with self-control, and self-control with endurance, and endurance with godliness, 7and godliness with mutual* affection, and mutual* affection with love. 8For if these things are yours and are increasing among you, they keep you from being ineffective and unfruitful in the knowledge of our Lord Jesus Christ. 9For anyone who lacks these things is short-sighted and blind, and is forgetful of the cleansing of past sins. 10Therefore, brothers and sisters,* be all the more eager to confirm your call and election, for if you do this, you will never stumble. 11For in this way, entry into the eternal kingdom of our Lord and Saviour Jesus Christ will be richly provided for you.
12 Therefore I intend to keep on reminding you of these things, though you know them already and are established in the truth that has come to you. 13I think it right, as long as I am in this body,* to refresh your memory, 14since I know that my death* will come soon, as indeed our Lord Jesus Christ has made clear to me. 15And I will make every effort so that after my departure you may be able at any time to recall these things.
16 For we did not follow cleverly devised myths when we made known to you the power and coming of our Lord Jesus Christ, but we had been eyewitnesses of his majesty. 17For he received honour and glory from God the Father when that voice was conveyed to him by the Majestic Glory, saying, ‘This is my Son, my Beloved,* with whom I am well pleased.’ 18We ourselves heard this voice come from heaven, while we were with him on the holy mountain.
19 So we have the prophetic message more fully confirmed. You will do well to be attentive to this as to a lamp shining in a dark place, until the day dawns and the morning star rises in your hearts. 20First of all you must understand this, that no prophecy of scripture is a matter of one’s own interpretation, 21because no prophecy ever came by human will, but men and women moved by the Holy Spirit spoke from God.*
In what way do I lose the context?
AMEN! AMEN!
The theologian Karl Barth says we find God in our silence, and the more I become aware of the work of the Holy Spirit, the more heartily I agree with Barth. Nothing can impede the Holy Spirit from indwelling in those He will, but I as a Christian can confuse the realization of Him in my life by avoiding that silence. This might be one of reasons Jesus warned against vain and repetitious prayers.
A few years back I read a book called Embers, by Sandor Marai. A Hungarian, who left Hungary in 1948, remained in exile until the fall of Communism, at which time publication of his books was allowed there. Eventually, he relocated to San Diego, and died there. The book is about two soldiers in the Austro-Hungarian Empire who were the very best of friends, but because of an act of infidelity this friendship was destroyed. Sandor writes of the "male virtues: silence, solitude, the inviolability of one's word and women."
St. Peter was one of those people who couldn't be accused by the Scripture that warns against a lukewarm disposition. But he could be used as an illustration of the Scripture that admonishes us to let our yes mean yes, and our no mean no. He was a passionate man who couldn't always live up to the demands of passion, the greatest of which is courage. I don't say this to criticize Peter, and I would never imply that I think I would have not denied Jesus, if I were in the same situation. I'm quite sure I would have. It is a consolation to me that Jesus forgave him, as it is a consolation to me that He forgave Thomas his doubt, though He was standing right in front of him. Only lately have I begun to wonder what happened to all the other apostles He appointed. Their thoughts and actions are lost to us. Pity, to my way of thinking.
Earlier in the week, I read the last chapter of the Gospel of John.
Jesus and Peter15 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. 18 Truly, truly, I say to you, when you were young, you used to dress yourself and walk wherever you wanted, but when you are old, you will stretch out your hands, and another will dress you and carry you where you do not want to go.” 19 (This he said to show by what kind of death he was to glorify God.) And after saying this he said to him, “Follow me.”
St. Peter fulfilled the command or desire of Jesus in that he did feed His sheep. The part of this Scripture that haunts me a bit is the part that I've italicized. I don't doubt what St. John said about what it means, but his explanation does not fully satisfy me. It's a poignant piece of Scripture that shows the poignant side of Christ, and I really like it for that reason.