Deuteronomy 19:6
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.
Cross-reference
Deuteronomy 19:4 defines the condition of unintentional killing without prior hatred, which this verse applies to the avenger's pursuit.
Numbers 35:12 explains cities of refuge as protection from the avenger until trial, exactly the same principle as the concern in this verse.
Joshua 20:5 restates the same law: the manslayer is not handed over because the killing was unintentional and without prior hatred.
Numbers 35:19 commands the avenger to kill the intentional murderer, contrasting with the protection given to the accidental killer in this verse.
Numbers 35:27 provides the same legal rule: the avenger may kill the slayer outside the refuge city, reinforcing the protection system.
2 Samuel 14:7 mentions the avenger of blood in a narrative, illustrating the law's application in a family dispute over accidental killing.