How did the spies ruin the rectification of the sin of Adam HaRishon?
(13,20) “And how is the land - is it fat or lean, are there trees in it or not? And you shall be courageous and take from the fruit of the land. And the time was the time of the ripening of the first grapes.”
The Torah here is teaching a person who fears Hashem and wishes to be successful in his spiritual endeavors, and who on a certain day learned much Torah and who prayed correctly, that if, G-d forbid, he becomes even a tiny bit arrogant about his learning and davening, even at the last second of the day, he can destroy and ruin everything. Even at the last moment he needs tremendous protection and mercy to preserve his spiritual gains.
This is what the end of the posuk “and the time was the time of the ripening of the first grapes” alludes to. Because grapes allude to the Tree of Knowledge, according to the opinion that the forbidden fruit were grapes, and the month during which the spies were sent was the month of Sivan, which is particularly favorable for the rectification of the sin of eating from the Tree of Knowledge.
In the first year after Yisrael went out of Egypt they received the Torah during this month and the spiritual impurity which had entered the human body due to Adam’s sin ceased to exist, and they would have achieved complete rectification had they not subsequently sinned with the golden calf which caused the spiritual impurity to return. In the second year during this month they returned to the task of rectifying Adam’s sin, but on the 29th of Sivan, the last day of the month, they sent the spies. Thus, because they did not conduct themselves on this last day correctly, all their efforts at rectification were ruined.
This is the allusion of our posuk - “the time was the time of the ripening of the first grapes” - the time had arrived for the completion of the ripening of the grapes, the completion of the rectification of the sin of eating from the Tree of Knowledge.