The Parsha begins with a description of the agricultural benefits and national security that the Jewish nation will experience in the Land of Israel if the people observe the commandments of the Torah. Abarbanel is bothered by the fact that only physical rewards relevant to our physical existence are mentioned. Why doesn’t the Torah mention the most important reward for observing the commandments: the spiritual reward experienced by the soul after death in the World-to-Come.
Abarbanel relates six explanations from other commentators before stating his own answer.
Rambam: Ultimately, G-d wants us to observe the commandments without any expectation of reward. Even though the true reward is a purely spiritual one, the Torah mentions only the physical rewards since they will remove the obstacles that prevent us from serving G-d properly.
Ibn Ezra: Although the true reward is the spiritual one in the World-to-Come, it is difficult for most people to relate to this esoteric and mysterious concept. G-d mentions only the physical rewards and punishments, which are apparent to everyone.
Rabbeinu Bechaya: He explains (unlike the Ibn Ezra) that the immortality of the soul and its rewards in the World-to-Come are actually an intrinsic, universal and natural aspect of human understanding. The Torah comes to teach us that reward and punishment in the physical world is actually a profound illustration of the miraculous nature of Divine Providence, an idea not normally accessible to human reason. How else can we explain that man’s performance of a particular commandment can have a direct effect on weather or health?
Rabbeinu Nissim and Kuzari: The most important principle required to strengthen the commitment of the Jewish People to Torah observance is their direct experience with Divine Providence. From the beginning of history, with the exception of individuals like Avraham, even the most profound thinkers have viewed the universe as a clockwork mechanism governed by fixed laws. Their intellectual powers led them to seek a rational and logical explanation of all physical phenomena. The idea that these laws were the result of the will of an omnipresent G-d and could be overturned at any time for any individual or group was completely foreign. G-d knew that the only way to solidify the commitment of the Jewish nation was to demonstrate this Divine Providence in a tangible manner in the physical world. A promise of reward in the next world would not be sufficient.
Rav Saadiah Gaon: One of the attractions of idolatry was that it created a link between idolatrous practices and physical rewards. In order to counteract this belief, the Torah emphasizes that physical rewards are actually the result of refraining from these idolatrous practices and observing the commandments.
Rabbeinu Nissim and Kuzari: The reward for the soul in the next world is actually alluded to in several of the verses that describe the physical rewards at the beginning of the Parsha. For example: “I will place my sanctuary among you”, “I will walk among you”, I will be G-d onto you and you will be a people onto me.” All of these verses refer to the G-dly connection of our souls to a higher spiritual existence. Whereas other religions dismiss any possibility of real accomplishment in this world and point only to the next world, we believe that the soul, even while contained within the limitations of the body, is capable of attaining lofty heights of spirituality. In effect, the body follows the soul. The promise of physical or bodily rewards for the performance of the commandments demonstrates this reality. If the soul can achieve this when contained within the body, how much more so will it soar when it is freed in the next world! In effect, the promise of reward in this world is actually a promise of reward to our true essence, our souls.
Abarbanel: The Parsha focuses on physical rewards only because it is referring to the nation as a whole. When a majority of the nation is observing the commandments, then physical reward is possible. However, when a majority is negligent in its observance, their dire consequences enumerated later in the Parsha are possible. But the reward that accrues to the soul in the next world does not depend on the behavior of the nation as a whole. Rather, each of us is judged individually, regardless of the behavior or our brethren. When the nation is judged favorably and is physically rewarded, even the transgressors can benefit, and vice versa. But this is not the case for the soul’s ultimate reward and punishment.