John Gill Commentary 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." — Numbers 19:8 (ASV)

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 (Numbers 19:7) ; and that this is one distinct from him that sprinkled the blood, (Numbers 19:4Numbers 19:5) ;

and bathe his flesh in water :
in a like quantity, as the above Targum:

and shall be unclean until the even :
and, though washed, might not go into the camp until that time: this may signify, as before, that though the crucifixion of Christ was a very great sin, and done by wicked hands, yet was pardonable through the very blood that was shed by them, (Acts 2:23Acts 2:36Acts 2:38Acts 2:41) .