Parashas Masei · Passuk 35:19 · TT note 3
Chabad.org — English translation + Rashi
Torah Temimah points to Yerushalmi Makkos 2:5 (TT note on “בְּפִגְעוֹ בּוֹ”).
English: It was taught: From where [do we know] that even if he said “I am unable to confront him,” [the obligation remains]? From “when he encounters him, he shall put him to death.”
Halakhic persistence of the avenger’s duty even when he claims inability.
The blood-avenger’s duty is not cancelled by a claim of inability to face the killer; the verse requires the killing upon encounter in any event.