Bon Voyage

The disastrous episode of the spies that were sent to investigate Eretz Yisroel certainly seems to defy explanation. After all, Rashi comments that these twelve individuals were the leaders of their respective tribes. Yet they returned with intended information that would discourage their compatriots from going there. Hashem had guaranteed them that Eretz Yisroel would be a wonderful place to live so why did they indeed dissuade them?