John Wesley on Numbers 19:13

Whosoever toucheth - If this transgression be done presumptuously; for if it was done ignorantly, he was only to offer sacrifice. Defiled - By approaching to it in his uncleanness: for holy things or places were ceremonially defiled with the touch of any unclean person or thing. Is upon him - He continues in his guilt, not now to be washed away by this water, but to be punished by cutting off.