But Moses said introduces Moses’ response in verses 41-43 to the Israelites’ intention to invade Canaan. He strongly advises them not to do it.

Why now are you transgressing the command of the LORD, for that will not succeed?: With this rhetorical question Moses tells the people not to disobey God by invading Canaan because they will be unsuccessful. Contemporary English Version uses two strong statements here, saying “You’re disobeying the LORD! Your plan won’t work.” The command of the LORD is literally “the mouth of the LORD” (see 3.16). Commands and instructions were normally communicated orally.

Quoted with permission from de Regt, Lénart J. and Wendland, Ernst R. A Handbook on Numbers. (UBS Helps for Translators). Miami: UBS, 2016. For this and other handbooks for translators see here .