Yosef Karo, Shulchan Aruch — Choshen Mishpat 12
“ Paragraph 1- When two parties come to court and one is easygoing and one is tough, before the claims have been heard or even if they have been heard but the judge does not know which way the ruling leans towards, a judge may say I do not want to process this case lest the judge finds the tough party liable and such party will pursue the judge. Once he has heard their claims and knows which way the ruling leans towards, he is not permitted to say he does not want to process the case. If the judge has been appointed by the public, he must hear the case. ”
