Psalms 4:3: But know that the LORD hath set apart him that is godly for himself: the LORD will hear when I call unto him.
This article is the American Tract Society definition of sanctify. To make holy, or to set apart for God. Genesis 2:3: *And God blessed the seventh day, and sanctified it: because that in it he had rested from all his work which God created and made.* Exodus 19:23: *And Moses said unto the LORD, The people cannot come up to mount Sinai: for thou chargedst us, saying, Set bounds about the mount, and sanctify it.*
In the Old Testament, sanctification frequently denotes the ceremonial or ritual consecration of any person or thing to God: thus the Hebrews as a people were holy unto the Lord, through the covenant with its rites and atoning sacrifices. Exodus 31:13: *Speak thou also unto the children of Israel, saying, Verily my sabbaths ye shall keep: for it is a sign between me and you throughout your generations; that ye may know that I am the LORD that doth sanctify you.*
The Jewish tabernacle, altar, priest, etc., were solemnly set apart for the divine service. Leviticus 8:10: *And Moses took the anointing oil, and anointed the tabernacle and all that was therein, and sanctified them. 11 And he sprinkled thereof upon the altar seven times, and anointed the altar and all his vessels, both the laver and his foot, to sanctify them. 12 And he poured of the anointing oil upon Aaron*s head, and anointed him, to sanctify him.*
In the similar sense, men, *sanctified themselves* who made special preparation for the presence and worship of God. Exodus 19:10: *And the LORD said unto Moses, Go unto the people, and sanctify them to day and to morrow, and let them wash their clothes, 11 And be ready against the third day: for the third day the LORD will come down in the sight of all the people upon mount Sinai.*
Numbers 11:18: *And say thou unto the people, Sanctify yourselves against to morrow, and ye shall eat flesh: for ye have wept in the ears of the LORD, saying, Who shall give us flesh to eat? for it was well with us in Egypt: therefore the LORD will give you flesh, and ye shall eat.*
A day was sanctified when set apart for fasting and prayer. Joel 1:14: *Sanctify ye a fast, call a solemn assembly, gather the elders and all the inhabitants of the land into the house of the LORD your God, and cry unto the LORD,*
The Sabbath was sanctified when regarded and treated as holy unto the Lord. Deuteronomy 5:12: *Keep the sabbath day to sanctify it, as the LORD thy God hath commanded thee.*
All such sanctifications were testimonials to the holiness of God, and signified men*s need of moral sanctification, or the devotion of purified and obedient souls to his love and service. In a doctrinal sense, sanctification is the making truly and perfectly holy what was before defiled and sinful. It is a progressive work of divine grace upon the soul justified by the love of Christ. The believer is gradually cleansed from the corruption of his nature, and is at length presented *unspotted before the throne of God with exceeding joy.* The Holy Spirit performs this work in connection with the providence and word of God.
John 14:26: *But the Comforter, which is the Holy Ghost, whom the Father will send in my name, he shall teach you all things, and bring all things to your remembrance, whatsoever I have said unto you. 17:17 Sanctify them through thy truth: thy word is truth.*
The highest motives urge every Christian not to resist him, and seek to be holy even as God is holy. The ultimate sanctification of every believer in Christ is a covenant mercy purchased on the cross. He, who saves us from the penalty of sin, also saves us from its power; and in promising to bring a believer into heaven, engages also to prepare for heaven.