21 This is a lasting ordinance for them. “The man who sprinkles the water of cleansing must also wash his clothes, and anyone who touches the water of cleansing will be unclean till evening.

Read Numbers 19:21 Using Other Translations

And it shall be a perpetual statute unto them, that he that sprinkleth the water of separation shall wash his clothes; and he that toucheth the water of separation shall be unclean until even.
And it shall be a statute forever for them. The one who sprinkles the water for impurity shall wash his clothes, and the one who touches the water for impurity shall be unclean until evening.
This is a permanent law for the people. Those who sprinkle the water of purification must afterward wash their clothes, and anyone who then touches the water used for purification will remain defiled until evening.