Parah 6: Killers
Why is the Portion of Parah always read on the Shabbat following Purim? There is physical impurity and spiritual impurity. There is spiritual purity and spiritual impurity. We live in both worlds. Even when we have not actually become physically impure, such as through contact with a dead body, we can become spiritually impure through our words and thoughts. The Torah demands that we strive to live at the highest levels in both the physical and spiritual worlds.
On Purim we become Spiritual killers. We rejoice that the nation of Amalek was destroyed by Esther and Mordechai. We review the commandment to wipe out the memory of Amalek. We strive to spiritually wipe out the influence of Amalek in the world. We are attackers on Purim. We are fighters. We speak of killing, and it is impossible to spea, study and think of such things without some impact on our souls. Although we are enwrapped by a Mitzvah, we have touched the world of murder, we have spiritually tasted blood.
We read the portion of the Parah Adumah each year immediately after Purim to purify ourselves from any spiritual damage caused by seeing ourselves a killers, even of Amalek, even as part of a Mitzvah. (Machberes Avodas Hashem)