Charles Ellicott Commentary Numbers 32:13

"And Jehovah`s anger was kindled against Israel, and he made them wander to and fro in the wilderness forty years, until all the generation, that had done evil in the sight of Jehovah, was consumed." — Numbers 32:13 (ASV)

And he made them wander in the wilderness forty years.— Moses here declares the fulfilment of the prediction which he had announced in obedience to the Divine commandment at the time when the spies brought up an evil report of the land. (See Numbers 14:33-34.)