Rashi on Numbers 20:3/רש"י על במדבר כ׳:ג׳

1ולו גוענו — means, WOULD THAT WE HAD DIED.

2בגוע אחינו means, by the death of our brethren — i.e., by the pestilence. This tells us that death by thirst is worse than that (i.e., than death by pestilence).

3בגוע — This is a noun and means the same as במיתת אחינו, “by the death of our brethren”; and it would not be correct to explain (translate) it: “when our brethren died”, for if this were so, it should be voweled to read בִּגְוֹעַ.