Summary: Jesus is about to go to the cross to make the ultimate sacrifice for sin, and precedes that act with this lovely prayer of intercession and consecration.
How important is faithfulness in prayer? Dr. Wilbur Chapman often told of his experience when, as a young man, he went to become pastor of a church in Philadelphia. After his first sermon, an old gentleman said to him, "You're pretty young to be pastor of this church. But you preach the Gospel, and I'll help you all I can." Dr. Chapman thought, "Here's a crank." But the man continued: "I'm going to pray for you that you may have the Holy Spirit's power upon you. Two others have covenanted to join with me in prayer for you."
Dr. Chapman said, "I didn't feel so bad when I learned he was going to pray for me. The 3 became 10, 10 became 20, 20 became 50, 50 became 200 who met before every service to pray that the Holy Spirit might come upon me. I always went into my pulpit feeling that I would have the anointing in answer to the prayers of those who had faithfully prayed for me. It was a joy to preach! The result was that we received 1,100 into our church by conversion in three years, 600 of whom were men. It was the fruit of the Holy Spirit in answer to prayer!"
A. Just how powerful is prayer? Prayer is the most powerful mechanism available to the believer. It transcends language, intellect, understanding and ability. It calms the saint and confounds the sinner. God hears prayers offered privately and publicly, from a whisper to a shout. He delights in the prayers of the earnest; educated or uneducated, prince or pauper. Those who are diligent in the discipline of prayer can share experiences of prayers God answered that still astonish you.
B. Jesus prayed, too. This morning we explore the longest prayer of Jesus that the Bible records. It is, what many regard as the real Lord’s prayer, as opposed to the model prayer that Matthew and Luke record in their gospels (Mt. 6:9-13, Lk. 11:2).
C. Bible publishers designate John 17 as “The High Priestly Prayer”, placing Jesus (symbolically) in the role of High Priest. It may be helpful to understand the role of priests in scriptural context.
1. A priest had two primary functions;  to offer sacrifices to God for the sins of the people, and  make continual intercession for those under their authority that come to God. (If you want a great study on the priesthood of Jesus, discover Hebrews.)
2. Jesus is about to go to the cross to make the ultimate sacrifice for sin, and precedes that act with this lovely prayer of intercession and consecration. OYBT Jn. 17.
A. Jesus’ farewell discourse is finished; he shared with his disciples what they needed to know. He warns them of the hatred the world will show towards them, but concludes the discourse with the words “Be of good cheer, I have overcome the world” (16:33).
B. He now lifts his eyes toward heaven and begins to pray. His prayer connects intimately with the discourse of chs. 14-16; this is evident in the transitional phrase “After Jesus said this”. His prayer is personal, but not private. He wants the disciples to hear him pray; for their edification (instruction) and encouragement.