Parashat Ki Teitzei concludes with two Mitzvot. The first is the Mitzvah to use fair and honest weights and measures, and the second is to remember Amaleik's unprovoked attack against Bnei Yisrael. Rashi explains the juxtaposition of these two Mitzvot by saying that the neglect of the first Mitzvah (use of fair and honest weights) will lead to the event remembered by the second (the attack of Amaleik). In other words, attacks by nations and people such as Amaleik come as a punishment for the sin of dishonest business conduct.
The Netziv, in his commentary on Chumash (HaEimek Davar), notes a fairly obvious irony that emerges from Rashi's claim. The original attack by Amaleik, of course, occurred in the wilderness, shortly after the Exodus. It is hard to believe that at this point the Bnei Yisrael engaged in business. How, then, can Rashi say that Amaleik's attack came in response to corruption in the Bnei Yisrael’s business? Furthermore, the Netziv asks, what sets this particular prohibition apart from all other Aveirot? Why does the Torah single out this specific type of stealing as warranting such a harsh punishment?
The Netziv explains, as Rashi himself writes in Parashat BeShalach (Shemot 17:8), that Hashem sent Amaleik against the Bnei Yisrael for a different reason. Just before Amaleik attacked, Bnei Yisrael complained about the lack of water to drink. They asked, "HaYeish Hashem BeKirbeinu Im Ayin?" "Is Hashem in our midst, or not?" (Shemot 17:7). Rashi explains that Amaleik's offensive came as a punishment for this lack of faith in Hashem. How can we fit this comment of Rashi with his remark in our Parashah, that Amaleik punishes Bnei Yisrael for the sin of dishonest weights and measures?
The Netziv answers by distinguishing classic theft from using inaccurate weights and measures in business. A person who steals on occasion does so out of greed; deceiving one's customers with dishonest weights and measures involves more than greed. By stealing from one’s own customers, one's entire financial life transforms into a corrupt system. By including dishonesty in the standard procedures by which the individual manages his business, he establishes corruption as an integral part of his income. This extends beyond greed; it involves a lack of faith. Resorting to dishonest practices to secure a livelihood reflects an absence of trust in Hashem's ability to provide. Someone with a proper, honest living who occasionally cheats is plagued by greed; one whose entire livelihood is based on deception is someone who lacks sufficient trust in Hashem.
When we express our doubt in Hashem's ability to provide for our needs He responds by removing His protective shield, which leaves us vulnerable to the hostility of our enemies. He did so the first time, and if we remove our trust in Him, the Torah warns, even in the arena of business and commerce, He will do so again. The Torah therefore commands us to conduct ourselves honestly in business, to protect ourselves from enemies such as Amaleik.
Adapted from a Devar Torah by Rabbi David Silverberg