9 Then someone who is ceremonially clean will gather up the ashes of the heifer and deposit them in a purified place outside the camp. They will be kept there for the community of Israel to use in the water for the purification ceremony. This ceremony is performed for the removal of sin.
Matthew Henry's Commentary on Numbers 19:9
Commentary on Numbers 19:1-10
(Read Numbers 19:1-10)
The heifer was to be wholly burned. This typified the painful sufferings of our Lord Jesus, both in soul and body, as a sacrifice made by fire, to satisfy God's justice for man's sin. These ashes are said to be laid up as a purification for sin, because, though they were only to purify from ceremonial uncleanness, yet they were a type of that purification for sin which our Lord Jesus made by his death. The blood of Christ is laid up for us in the word and sacraments, as a fountain of merit, to which by faith we may have constant recourse, for cleansing our consciences.