Parashas Masei · Passuk 35:23 · TT note 4
Chabad.org — English translation + Rashi
Torah Temimah points to Sanhedrin 29a (TT note on “וְהוּא לֹא אוֹיֵב לוֹ”).
E-Daf — Sanhedrin 29a · Sefaria
English: Our Rabbis taught: “And he was not his enemy and did not seek his harm” — one [phrase] for a judge and one for two Torah scholars who hate each other, who may not sit in judgment together.
Application of the “not an enemy” language to judicial disqualification.
The verse’s requirement that the killer not be an enemy is also used to bar judges or scholars who harbor mutual enmity from adjudicating together.