NET

6 Otherwise the blood avenger will chase after the killer in the heat of his anger, eventually overtake him, and kill him, though this is not a capital case since he did not hate him at the time of the accident.

Darby

6 lest the avenger of blood pursue the manslayer, while his heart is hot, and overtake him, because the way is long, and smite him mortally; whereas he was not worthy of death, since he hated him not previously.

KJV

6 Lest the avenger of the blood pursue the slayer, while his heart is hot, and overtake him, because the way is long, and slay him; whereas he [was] not worthy of death, inasmuch as he hated him not in time past.