Halakhah zu Dewarim 1:15

Its laws - such as that which they, may their memory be blessed, said (Midrash Tanchuma 5:3) that just as the one who is fit to be a judge must know the laws of the Torah, so too must he be someone of [good] character traits and a proper man, so that the judged not say to him, "Take out the beam from between your eyes," meaning to say, "adorn yourself [first] and afterwards adorn others" (Sanhedrin 18a); that, behold, it states in the Torah concerning judges (Deuteronomy 1:15), "wise men," meaning to say, those that know the wisdom to judge truthfully, "and known to your tribes," [meaning] that the spirit of men derive pleasure from them, "men of strength," that they are valiant about the commandments, exacting upon themselves and suppress their [evil] inclinations to the point that they do not have any disgrace and any ugliness, and their teaching is beautiful, and [also] included in being men of strength is that they have a brave heart to save the oppressed from the oppressor, like the matter that is stated (Exodus 2:17), "and Moshe rose to save them," and just like our teacher Moshe, peace be upon him, was humble, so too must every judge be humble; and the rest of its details - are elucidated in Sanhedrin in [various] scattered places (see Tur, Choshen Mishpat 18).