אֵין עֵד נַעֲשֶׂה דַּיָּן

ביטוי (אנגלית)

A witness cannot act as judge

הגדרה (אנגלית)

Someone who has personally witnessed a certain event cannot judge the same matter. One who has personal knowledge of a disputed issue cannot serve as a judge in that case, since he is no longer neutral regarding the matter.

("But at night, even three may write and not judge. What is the reason? Because they are witnesses, and a witness cannot become a judge"—Bava Batra 114a, and similarly: "Even if an agent becomes a witness, a witness cannot become a judge"—Rashi, Gittin 5b)