Midrasz do Kapłańska 16:26

1) (Vayikra 16:26) ("And he who sends the he-goat to Azazel shall wash his clothes and bathe his flesh in water, and then he may come to the camp.") "And he who sends": not he who sends the sender (i.e., not those who accompany him). "And he who sends the he-goat to Azazel shall wash his clothes": I might think that his clothes become unclean as soon as he leaves the wall of the azarah (the Temple court). It is, therefore, written "to Azazel (he) shall wash his clothes." If "to Azazel (he shall wash his clothes," I might think that his clothes do not become unclean until he reached Tsok (the mountain from which the goat was precipitated). And he who sends the goat to Azazel shall wash his clothes." How (are these verses to be reconciled)? As soon as he leaves the wall of Jerusalem his clothes become unclean. These are the words of R. Yehudah.

2) R. Yossi says: "to Azazel (he) shall wash his clothes": His clothes do not become tamei until he reaches Tsok. R. Shimon says: He who sends the he-goat to Azazel shall wash his clothes": He thrusts it headlong (down the mountain) and his clothes become tamei.

3) "he shall wash his clothes and bathe his flesh in water": I might think that it is a decree of the King (that he must immerse, just as the high-priest does); it is, therefore, written "and then he may come to the camp." Just as "and then he may come to the camp" there (in respect to the red heifer [Bamidbar 19:7]) (means that he may immerse) to free himself of tumah; here, too, (it means) to free himself of tumah, (but if he wishes to prolong his state of tumah, he need not immerse.)