Numbers 19:8 (BSB)

The one who burned the heifer must also wash his clothes and bathe his body in water, and he too will be ceremonially unclean until evening.

From Numbers 19. Also in the ESV.

Commentary on Numbers 19:8

• Matthew Henry (Presbyterian), Matthew Henry's Complete Commentary on Numbers 19:1-10: We have here the divine appointment concerning the solemn burning of a red heifer to ashes, and the preserving of the ashes, that of them might be made, not a beautifying, but a purifying, water, for that was the utmost the law reached to; it offered not to adorn as the gospel does, but to cleanse only.
• John Gill (Reformed Baptist), Exposition of the Old and New Testaments on Numbers 19:8: And he that burneth her shall wash his clothes in water,.... In forty seahs of water, as the Targum of Jonathan: this shows that one different from this is designed in Num 19:7; and that this is one distinct from him that sprinkled the blood, Num 19:4, and bathe his flesh in water: in a like quantity, as the above Targum: and shall be unclean...
• Geneva Bible Notes (Reformed), Geneva Bible Study Notes on Numbers 19:8: And he that burneth her shall wash his clothes in water, and bathe his flesh in water, and shall be unclean until the even. (d) The inferior priest who killed her, and burned her.
• Keil & Delitzsch (Lutheran), Biblical Commentary on the Old Testament on Numbers 19:2-10: Num 19:2-10 Preparation of the Purifying Water. - As water is the ordinary means by which all kinds of uncleanness are removed, it was also to be employed in the removal of the uncleanness of death. But as this uncleanness was the strongest of all religious defilements, fresh water alone was not sufficient to remove it; and consequently a certain kind of sprinkling-water was appointed...