Rashi explains that after forty years of travel in the desert, Klal Yisrael had attained a sublime level of dignity. They perceived gadlus Ha’Boreh, the greatness of Hashem, and appreciated the boundless beneficence He had showered upon them. They realized that their remarkable military prowess, as well as their continued success and well-being could only be attributed to Hashem’s generosity. At this juncture, Hashem chose to make an agreement (covenant) with Klal Yisrael so that they would not forget all that transpired these forty years. He wanted them to reflect upon their source of strength and not take personal credit for their achievement.
One would think that after Klal Yisrael had reached such a lofty level in their comprehension of Hashem, such an agreement would have been superfluous. Would it not have been more propitious to admonish them in hakoras ha’tov, appreciation of Hashem, at a time when their emunah was weak? Do you discuss the possibility of a person falling immediately after he has emerged victorious?
Horav Henach Leibovitz, Shlita, asserts that the Torah is teaching us an exceptional lesson in human nature. When a person reaches higher levels of spiritual perfection, he must become wary of the subterfuge of the yetzer hora, evil inclination. Specifically at this time, the yetzer hora suggests to a person that he has nothing about which to be concerned.
After forty years of wandering in the desert, being regularly sustained by Hashem, Bnei Yisrael reached an incomparable degree of gratitude to Hashem. This was the most appropriate time to warn them not to forget the lesson which was imbued in them throughout four decades of travel. Hashem reminded Bnei Yisrael that regardless of their feelings of security and success, they were not to permit these delusions of grandeur to become a guiding force. They were still apt to fall into the clutches of the yetzer hora. Indeed, at a time like this they were probably more vulnerable, so that greater vigilance was essential.
