Deuteronomy 4:42

so that someone who committed manslaughter could flee there, [that is, a person] who killed his neighbor unintentionally and without previously having hostility toward him, and that by escaping to one of these cities he might [claim the right of asylum and] save his life:

Numbers 35:6

[Among] the cities which you give to the Levites shall be the six cities of refuge, which you shall provide for the one who commits manslaughter to flee to; and in addition to them you shall give forty-two cities [to the Levites].

Numbers 35:11-12

then you shall select for yourselves cities to be cities of refuge, so that the one who kills any person unintentionally may escape there.

Numbers 35:15-28

These six cities shall be a refuge for the Israelites and for the stranger and the resident alien among them; so that anyone who kills a person unintentionally may escape there.

Deuteronomy 19:1-10

“When the Lord your God cuts off (destroys) the nations whose land He is giving you, and you dispossess them and live in their cities and in their houses,

Hebrews 6:18

so that by two unchangeable things [His promise and His oath] in which it is impossible for God to lie, we who have fled [to Him] for refuge would have strong encouragement and indwelling strength to hold tightly to the hope set before us.

Treasury of Scripture Knowledge

Summary

That the slayer might flee thither, which should kill his neighbour unawares, and hated him not in times past; and that fleeing unto one of these cities he might live:

Bible References

General references

Deuteronomy 19:1
“When the Lord your God cuts off (destroys) the nations whose land He is giving you, and you dispossess them and live in their cities and in their houses,
Numbers 35:6
[Among] the cities which you give to the Levites shall be the six cities of refuge, which you shall provide for the one who commits manslaughter to flee to; and in addition to them you shall give forty-two cities [to the Levites].
Hebrews 6:18
so that by two unchangeable things [His promise and His oath] in which it is impossible for God to lie, we who have fled [to Him] for refuge would have strong encouragement and indwelling strength to hold tightly to the hope set before us.