Jamieson, Fausset and Brown on Leviticus 16:23-28

23-28. Aaron shall come into the tabernacle of the congregation, and shall put off the linen garments--On the dismissal of the scapegoat, the high priest prepared for the important parts of the service which still remained; and for the performance of these he laid aside his plain linen clothes, and, having bathed himself in water, he assumed his pontifical dress. Thus gorgeously attired, he went to present the burnt offerings which were prescribed for himself and the people, consisting of the two rams which had been brought with the sin offerings, but reserved till now. The fat was ordered to be burnt upon the altar; the rest of the carcasses to be cut down and given to some priestly attendants to burn without the camp, in conformity with the general law for the sin offerings (Le 4:8-12; 8:14-17). The persons employed in burning them, as well as the conductor of the scapegoat, were obliged to wash their clothes and bathe their flesh in water before they were allowed to return into the camp.