Deuteronomy 25:19 "You shall erase the memory of Amalek"

When the Jewish people came out of Egypt, all the nations of the world stood in awe of this great miracle.

They all heard of the greatness of HaShem and the many wonders He performed for His chosen people.

They were convinced that they would be powerless against the Jewish nation.

Only Amalek dared to challenge HaShem.

Foolishly, the Amalekites declared war and attacked the Jewish people. Needless to say, they were defeated, for HaShem Himself fought for the nation of Israel.

Nevertheless, their battle had a very negative effect on the future of the Jewish nation. Afterwards, other nations also dared to question the strength of this new people. Thus, despite their fall, the Amalekites did much damage.

The Rabbis compared this to a steaming bathtub, too hot for anyone to climb into. Then, someone came along and plunged into the boiling water. He got scorched, but in the process of doing so, he cooled the water a bit, enabling others to enter.

Because Amalek was the first nation to doubt HaShem's power, we are commanded to destroy it entirely.