John Gill Commentary Numbers 14:15

"Now if thou shalt kill this people as one man, then the nations which have heard the fame of thee will speak, saying," — Numbers 14:15 (ASV)

Now [if] you shall kill [all] this people, as one man
Suddenly, and at once, as might be done by a pestilence; and as 185,000 were smitten at once, and as thought by the same disease, by the Angel of the Lord in the camp of the Assyrians, in later times, (2 Kings 19:35) ;

then the nations which have heard the fame of you ;
the Egyptians, Canaanites, and others, as Aben Ezra observes; who had heard the report of the wonderful things done by him for Israel, and of the great favours he had bestowed upon them, and so of his power, and goodness, and other perfections displayed therein, which made him appear to be preferable to all the gods of the Gentiles:

will speak, saying ;
as follows.