Albert Barnes Commentary Numbers 13:32

"And they brought up an evil report of the land which they had spied out unto the children of Israel, saying, The land, through which we have gone to spy it out, is a land that eateth up the inhabitants thereof; and all the people that we saw in it are men of great stature." — Numbers 13:32 (ASV)

A land that eateth up ... - that is, it is a land which from its position is exposed to incessant attacks from one quarter and another, and so its occupants must always be armed and watchful.