Sforno on Numbers 20:13/ספורנו על במדבר כ׳:י״ג

1ויקדש בם, by these very waters G’d did become sanctified later on in the incident which occurred at the river Arnon when He showed these people these unnatural waters as testified to by the Israelites in their song (21,19) ומנחליאל במות that these waters instead of flowing downwards in accordance with the laws of gravity, actually flowed uphill.