In Numbers 19, the Torah gives the laws for preparing the ashes of the red heifer. The red heifer is an unusual sacrifice which was slaughtered and burned outside of the Tabernacle. Its ashes were then collected and mixed with water. The water was sprinkled in a purification ceremony which removed ritual uncleanness engendered by contact with death.
Paradoxically, the preparation of the red heifer renders each person involved unclean. The priest who oversees the slaughter and the burning becomes unclean and incurs first degree impurity. The man who ignites the fire becomes unclean. The man who gathers the ashes together is rendered unclean. Moreover, the one who sprinkles the water of cleansing to remove the impurity of corpse contamination incurs first degree impurity. The sages speak of the paradox as an inexplicable decree of the Almighty:
Who decreed this? Was it not … God? We have learned that all the people engaged in preparing the water of the ashes of the red heifer, from beginning to end, defile garments, while the heifer itself makes garments ritually clean. The Holy One, blessed is He, says, “I have laid down a statute; I have issued a decree! You cannot transgress My decree.” (Numbers Rabbah 19:1)
The same paradox is also present in the rituals of Yom Kippur. After completing the purification ceremony of Yom Kippur, the high priest needed to immerse again. Similarly, the man who released the goat into the wilderness needed to immerse before returning to the camp, and the priest who oversaw the burning of the carcasses of the sin offerings needed to immerse himself before returning to the camp.
The purification paradox hints toward Messiah who became unclean in order to cleanse. To save others from death He died. Yeshua took on mortal uncleanness by virtue of His human birth. He took on human uncleanness by virtue of His healing ministry in our midst. He took on the uncleanness, the iniquity, the transgression, and sin of Israel. He took on the contaminating impurity of death itself, in order to cleanse us from sin and death. He did not remain long in a state of ritual impurity. Human uncleanness and iniquity did not cling to Him. He stepped out from the tomb in perfect purity. He shed the mortal form, and with it He shed ritual impurity. The unclean grave clothes, tainted with the contamination of death, He left behind.
The writer of the book of Hebrews specifically mentions in Hebrews 9:13-14 the ashes of the red heifer. What is more, he attributes efficacy to them as regards cleansing the flesh. The passage compares the blood of Messiah to the ashes of the red heifer. If the ashes of the red heifer work on the outside (the flesh), how much more so does the blood of Messiah work on the inside (the conscience) from sin:
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 Messiah, who through the eternal Spirit offered Himself without blemish to God, cleanse your conscience from dead works to serve the living God? (Hebrews 9:13-14)