Deuteronomy 19:4
And this is the case of the slayer, which shall flee thither, that he may live: Whoso killeth his neighbour ignorantly, whom he hated not in time past;
Cross-reference
Deuteronomy 19:6 gives the logical consequence — the avenger of blood pursuing the manslayer, justifying the need for refuge.
Deuteronomy 4:42 repeats the exact same definition of unintentional manslaughter that qualifies for asylum.
Deuteronomy 17:8 deals with difficult homicide cases requiring higher judgment, linking to the legal context of unintentional killing here.
Numbers 35:15-24 expands on the criteria for unintentional killing and the protection of cities of refuge.
Exodus 21:13 is the earlier law that appoints a place of refuge for unintentional killers, directly paralleling this condition.
Numbers 35:11 establishes the same law of cities of refuge for unintentional killers, providing the foundational legislation that Deuteronomy 19:4 restates.
2 Samuel 14:11 narrates a plea for refuge from the avenger, directly applying the principle of protection for unintentional killers.