NUMBERS 13:27

The spies’ slanderous report against Eretz Yisrael is one of the worst, if not the single gravest, sin described in the Bible. Moshe sends one representative from each tribe to scout out the land, and ten of the twelve return with a negative report. Only Kalev and Yehoshua have faith in Hashem and speak positively about the Land of Israel. Whereas Hashem forgives many sins throughout the Bible, slandering Eretz Yisrael is unacceptable, and the entire generation is punished for accepting the report. They are condemned to wander in the desert for forty years until the entire generation of the spies dies, as they no longer deserve to enter the Promised Land. Like Kalev and Yehoshua, we must not fall into the trap of criticizing the greatest of all God’s gifts. Rather, we must speak positively about Israel at every opportunity.

Source: Israel in the News