Mishnayos Zevachim Perek 11 Mishnah 4

With regard to the garment mentioned explicitly in the Torah, and the sackcloth, and the hide, all of these require laundering. And the laundering must be performed in a sacred place, the Temple courtyard, and the breaking of an earthenware vessel in which a sin offering was cooked must be performed in a sacred place, and scouring and rinsing of a copper vessel in which a sin offering was cooked must be performed in a sacred place. With regard to this matter, a stringency applies to a sin offering more than it applies to offerings of the most sacred order.

אֶחָד הַבֶּגֶד וְאֶחָד הַשַּׂק וְאֶחָד הָעוֹר, טְעוּנִין כִּבּוּס בְּמָקוֹם קָדוֹשׁ. וּשְׁבִירַת כְּלִי חֶרֶס, בְּמָקוֹם קָדוֹשׁ. וּמְרִיקָה וּשְׁטִיפָה בִּכְלִי נְחשֶׁת, בְּמָקוֹם קָדוֹשׁ. זֶה חֹמֶר בַּחַטָּאת מִקָּדְשֵׁי קָדָשִׁים: