Numbers 19 The Lord adds another command/ordinance onto the many that He has given to the nation of Israel.  This one involves a red heifer.   Everything is a bit different with this sacrifice.  It was taken "outside" the camp to be slaughtered.  Eleazar, the priest, was in charge of the slaughtering.  Then it was completely burned along with cedar, hyssop, and scarlet material.  The ashes were gathered up and mixed with water.  This water was considered a means of purification.   Whenever a person came into contact with a dead body, he or she, or the whole tent.. would be sprinkled with this special water - on the 3rd day and again on the 7th day.
Eleazar had to wash and was unclean for that day when he slaughtered the heifer.
The person who did the burning was unclean for that day.
The person who gathered the ashes was unclean for that day.
A "clean" person was in charge of sprinkling the water on those who were unclean.
And anyone who did not follow this, but remained unclean... would be cut off from the assembly because he would defile the sanctuary.

Hebrews 9:13 " For if the blood of goats and bulls and the ashes of a heifer sprinkling those who have been defiled, sanctify for the cleansing of the flesh, how much more will the blood of Christ, who through the eternal Spirit offered Himself without blemish to God, cleanse your conscience from the dead works to serve the living God?"   Every part of the old covenant sacrifices were mere copies of what was yet to come, when Jesus Christ, Himself.. " at the consummation of the ages" was "manifested to put away sin by the sacrifice of Himself." (v26).   For, " He, having offered one sacrifice for sins, for all time, sat down at the right hand of God.... For by one offering He has perfected for all time those who are sanctified." ( 10:12,14)  "By this will we have been sanctified though the offering of the body of Jesus Christ once for all."( 10:10) 

  So, "let us draw near with a sincere heart in full assurance of faith, having our hearts sprinkled clean from and evil conscience and our bodies washed with pure water.  Let us hold fast the confession of hope without wavering, for He who promised is faithful." Hebrews 10:22-23

2 more thoughts from the writer of Hebrews:
13:11-12 " For the bodies of those animals whose blood is brought into the holy place by the high priest as an offering for sin are burned outside the camp. Therefore Jesus also, that He might sanctify the people through His own blood suffered outside the gate." 
and
13:15-16 " Through Him then, let us continually offer up a sacrifice of praise to God, that is, the fruit of lips that give thanks to His name. And do not neglect doing good and sharing for with such sacrifices God is pleased." 

Father in Heaven,  You are Mighty and Holy and highly to be praised.  We offer You our sacrifices of praise and thanksgiving, for You have given us Your Son, Jesus Christ, who puts away our sin by the sacrifice of Himself, once for all, completely and thoroughly!  Hallelujah, What a Savior!!
God of peace, who has brought us "up from the dead... through the blood of the eternal covenant, even Jesus our Lord",  will You equip us " in every good thing to do (Your) will, working in us that which is pleasing in (Your) sight, through Jesus Christ, to whom be the glory forever and ever. Amen"
 ( Hebrews 13:20-21)