Parsha Mitzvot: Tzav: Mitzvah 131 – Concept 376: The Soul’s Honor
“The Kohen shall don his fitted linen tunic, and he shall don linen breeches on his flesh; he shall separate the ash of what the fire consumed of the elevation-offering on the Altar, and place it next to the Altar (Vayikra 6:3).” We are commanded to remove the ashes from the Altar every day (Rambam, Hilchot Timidim u’Mussafim – The Laws of the Constant and Additional Offerings).
Once the sinner has received his punishment, and his “physical” sin has been consumed on the Altar, we must remove any memory and never mention his sin again. We clean the ashes to state that his sin is gone, never to be mentioned again. (Rabbi Menachem ha-Bavli)