"For their sakes I sanctify Myself, that they themselves also may be sanctified in truth.John 17:19(NASB)
The word 'sanctify' means 'set apart' and in this amazing high priestly prayer, where Jesus prays for his disciples to be 'set apart unto God' through the truth of the Word of God, He also sanctifies Himself: "For their sakes I sanctify Myself so that they themselves also may be sanctified in truth."
Jesus sanctified Himself to do the will of the Father. He set Himself apart unto God in order to carry out the redemptive plans and purposes that God had prepared for Him to do. He did this so that all who believe in Him might also be sanctified unto God, set apart unto Him to live and work to His praise and glory. Christ sanctified Himself so that all who believe on His name might also be sanctified and set apart unto God - in truth.
The Lord Jesus was sent into a world of men as a Man, to be the perfect sinless Son of Man and to live a perfect sinless human life. He did this so that the character and attributes of the one, eternal, omniscient, holy God might be revealed to the fallen race of man through His only begotten Son, our Saviour, Jesus Christ.
Christ was set apart to be God's witness on earth to represent God in the world and to become the federal-head of a new creation of people to be sanctified unto God.
But the Lord Jesus also was given to the world to die for the sin of the whole world so that all who believe on His name might be sanctified and set apart unto God. And then in His absence they too might become God's witness on earth to represent God in this fallen world and to become a new creation in Christ: "To be sanctified unto God."
Christ sanctified Himself to do the will of God on earth for our sakes and to set us an example of how God desires that man should live i.e. in total dependence upon Him and willing to say, "Thy will not mine be done." Christ is the perfect pattern of a man set apart unto God, and He sanctified Himself so that we might be sanctified in HIM - in spirit and in truth.
Heavenly Father, thank You for giving Jesus to be my Saviour and for sending Him to be my example of how a man, sanctified unto God, should live. I pray that in the power of the Holy Spirit I may live my life sanctified unto God, walking in spirit and truth, and living my life in total dependence upon You, to Your praise and glory. In Jesus' name I pray, AMEN.