Mishnah, — Seder Nezikin, Tractate SanhedrinChapter 2
“ Mishnah 1 The High Priest can judge and be judged himself, can serve as a witness and others can witness against him, can perform Levirate nullification and others can perform Levirate nullification for his widow, and others can marry her through Levirate marriage, but he cannot marry another through Levirate marriage, because it is forbidden for him to marry a widow. (Someone close to him) dies, he cannot follow the coffin, except when they enter he is not there, and they are not there when he enters. ”
