The Torah portion concludes with the commandment to remember and destroy Amalek, the nation that initiated a war with the Israelites when they left Egypt. According to the Sages, the commandment to remember the actions of Amalek is, indirectly, a way for God to remind the Israelites of their sin at Refidim (Exodus 17:7), for which they were punished with Amalek’s waging war against them.

“Remember that which Amalek did to you” (Deuteronomy 25:17). “Amalek” is an allusion to am lek, meaning a nation [am] that came to lick [lek] the blood of the Israelites, as does a dog. Rabbi Levi said in the name of Rabbi Shimon ben Halafta: To what could the Amalekites be compared? They could be compared to a fly that was eager to get to a bloody wound; so too, the Amalekites were eager to attack Israel, as does a dog.

The Sages taught in the name of Rabbi Natan: Amalek traveled four hundred parasangs to wage war with Israel in Refidim…. The verse states that Amalek attacked “on the way upon your exodus from Egypt” (25:17). Rabbi Levi said: This teaches that Amalek attacked the Israelites from the road, like highwaymen.

This can be explained by means of a parable of a king who had a vineyard and surrounded it with a fence, and placed a biting dog there. The king said: The dog will bite anyone who comes and breaches the fence. Sometime later, the king’s son came and breached the fence and the dog bit him. Whenever the king sought to evoke his son’s sin of breaching the vineyard, he would say to him: Remember that the dog bit you. So too, anytime the Holy One, blessed be He, sought to evoke the Israelites’ sin that they did in Refidim when they said: “Is the Lord among us, or not?” (Exodus 17:7), He would say to them: “Remember that which Amalek did to you.” (Tanĥuma [Buber], Ki Tetze)