John 17:19

Sanctify - To be sacred and set apart.

I sanctify myself - I consecrate and devote myself to death - that I may thereby purchase eternal salvation for them. There seems to be here an allusion to the entering of the high priest into the holy of holies, when, having offered the sacrifice, he sprinkled the blood before the ark of the covenant. So Jesus entered into the holiest of all by his own blood, in order to obtain everlasting redemption for men: see Hebrews 9:11-13. The word, ἁγιαζω, to consecrate or sanctify, is used in the sense of devoting to death, in Jeremiah 12:3, both in the Hebrew and in the Septuagint: the Hebrew קדש signifies also to sacrifice.

I sanctify myself - I consecrate myself exclusively to the service of God. The word "sanctify" does not refer here to personal sanctification, for he had no sin, but to setting himself apart entirely to the work of redemption.

That they also ... -

1. That they might have an example of the proper manner of laboring in the ministry, and might learn of me how to discharge its duties. Ministers will understand their work best when they most faithfully study the example of their great model, the Son of God.

2. That they might be made pure by the effect of my sanctifying myself - that is, that they might be made pure by the shedding of that blood which cleanses from all sin. By this only can men be made holy; and it was because the Saviour so sanctified himself, or set himself to this work so unreservedly as to shed his own blood, that any soul can be made pure and fit for the kingdom of God.

17:19 I sanctify myself - I devote myself as a victim, to be sacrificed.