Parashas Masei · Passuk 35:12 · TT note 1
Chabad.org — English translation + Rashi
Torah Temimah points to Makkos 12a (TT note on “עַד עׇמְדוֹ”).
English: “Until he stands before the congregation for judgment” — why is this said? Because it is written “the blood-avenger shall kill the murderer; he has no blood,” one might think [he may kill] immediately; therefore Scripture says “until he stands before the congregation for judgment.”
Halakhic limit on the blood-avenger — no killing before trial.
Even though the blood-avenger is given authority, he may not kill the accidental killer until the latter has stood trial before the court.