In Exodus 19, Israel came to Mt. Sinai. Verse 1 says it was “on the third new moon” that they arrived at Sinai since they left Egypt. Verses 11 tells us that Israel was to prepare herself for “the third day” when “the LORD will come down on Mount Sinai in the sight of all people.” Verses 16-20 tell of the great majesty and glory of God who appeared to Israel on “the third day” on top of Mt. Sinai in fire, smoke, thunder, and lightening. While Moses was on the mount he received the Ten Commandments and the Book of the Covenant. Thus, Israel’s covenant inauguration/renewal ceremony took place on the third day. The prologue to the Ten Commandments reiterates this resurrection theme when God says, “I am the LORD you God who brought you out of the land of Egypt, out of the house of slavery.” This is resurrection language. “You were once dead in Egypt, but now you are alive, therefore serve me” is the essence of what God is saying. This proclamation takes place not just on the third day, but on the third day of the third month/third new moon.
“Exodus 19:1 tells us that Israel arrived “on the third new moon” (literally) from the month they left Egypt. They had departed on the 15th day of the first month, so that they arrived at Sinai at the beginning of the week. On the second day, Moses went up the mountain of God, and God told him that He was going to make covenant with Israel. Moses came down from the mountain and told the people, who rejoiced to have the Lord as their God (w. 2-8a). The third day, Moses told God what the people had said, and God told him that He would speak to Israel from the cloud of glory. Moses returned and told this to the people (VV. 8b-9). The fourth day, Moses returned to hear what God had to say next, and God told him to tell the people to prepare themselves to receive the covenant on the third day, which would be the sixth day of the week. Adam was created on the sixth day of the creation week, and was established in covenant with God. Since, as we have seen, the Sinaitic covenant is a redemptive specification or republication of the Old Adamic Covenant (from one Biblical perspective, at least), it is telling that God “re-creates” humanity in covenant with Himself on this sixth day of the week.” 
It is interesting that God told Moses to “consecrate the people today and tomorrow, and let them wash their garments and be ready for the third day” (Ex. 19:10). Israel needed to be cleansed from their uncleanness, which is symbolic death. They were symbolically dead in Egypt and needed to be raised to life again, which was to take place on the third day when the covenant was going to be ratified/renewed. Thus we can agree with Jordan that the “process of covenant renewal with man dead in sins and trespasses must involve resurrection.”
This brings us then to Numbers 19:11-13.
11 “Whoever touches the dead body of any person shall be unclean seven days. 12He shall cleanse himself with the water on the third day and on the seventh day, and so be clean. But if he does not cleanse himself on the third day and on the seventh day, he will not become clean. 13Whoever touches a dead person, the body of anyone who has died, and does not cleanse himself, defiles the tabernacle of the LORD, and that person shall be cut off from Israel; because the water for impurity was not thrown on him, he shall be unclean. His uncleanness is still on him.”
This passage makes it very clear that death needs to be cleansed from a person on third day, as well as the on the seventh day. This is an obvious third day resurrection motif. But what might not be as obvious is why it is that the cleansing is needed on both the third and seventh days. Jordan gives us insight.
The third day (year, etc.) theme arises from the theology of the week. History begins on the first day, but humanity fell into sin and came under the judgment on [sic] death right away. There is a preliminary judgment and restoration on the third day, and that restoration makes it possible for humanity to become faithful and obedient as we move to the final, seventh day of history. This two judgment, two-resurrection scheme is set forth most fully in Numbers 19, where we read that a person who came into near contact with a human corpse was contaminated by death, just as all of us are contaminated with Adam’s death, and that the unclean person was cleansed both on the third day and again on the seventh. We see here a preliminary cleansing (that is, a resurrection from death contamination) and a final cleansing.
This analysis seems to fit with Jesus’ understanding of the flow of history in John 5. Jesus said “For an hour is coming (future) and is now here (present), when the dead will hear the voice of the Son of God, and those who hear will live.” The third day cleansing represents Christian baptism (the first resurrection) and the seventh day cleansing represents eschatological cleansing (the second resurrection). A person who has encountered death needs to be cleansed twice, once in the middle of history and once again at the end. The cleansing/resurrection in the middle of history and again at the end of history corresponds to the two cleansings/ two resurrections found in Numbers 19.
“The man who is unclean from contact with a corpse is to be cleansed on the third day and again on the seventh day. This double resurrection pattern is found all through the Scriptures. For instance, in John 5:21-29, Jesus distinguishes a first resurrection, when those dead in sin will hear the voice of Christ and live (v. 25); and a second resurrection, when those dead in the grave will come forth to a physical resurrection (v. 29). The first resurrection comes in the middle of history to enable men to fulfill the duties of the old creation. The second resurrection comes at the end of history to usher men into the new creation. Jesus was raised on the third day, thereby inaugurating the New Covenant in the midst of the week of history. Christians live between the third and seventh days of history, Spiritually resurrected and in the New Covenant, but physically mortal and assigned to complete the tasks of the Old Adamic Covenant. The fact that the law was given at Sinai on the third day, and in the third month, was a provisional anticipation of the third-day resurrection yet to come in Christ.”
Saint Paul also affirms this truth when he speaks of the resurrection in 1 Corinthians 15:23 – each in his own order: Christ the first-fruits, then at his coming those who belong to Christ will be resurrected.
 See James B. Jordan, The Law of the Covenant: An Exposition of Exodus 21-23 (Tyler, TX: Institute for Christian Economics, 1984), 55-56.
 Jordan, Law of the Covenant, 56.
 Jordan, The Handwriting on the Wall, A Commentary on the Book of Daniel (Powder Springs, GA: American Vision, 2007),130.
 Jordan, The Handwriting on the Wall, 58.
 David Chilton, Days of Vengeance: An Exposition of the Book of Revelation (Fort Worth, TX: Dominion Press, 1987), 550-551.