Acharei Mot - Shlishi
Don’t Scapegoat Me!
The messenger who brought the scapegoat to the wilderness would have to immerse himself and his clothes in a mikvah before returning to the camp. The remains of the sin offerings would be brought outside the camp and burned. The person who burned them likewise had to immerse himself and his clothes before returning to the camp.
All this was to be performed annually on Yom Kippur, the 10th day of the month of Tishrei, on which we fast and abstain from labor. This day is designated by G-d to atone for the Jews' sins each year. The High Priest had to be the one to perform the Yom Kippur service, wearing his linen garments.