Deuteronomy 4:42

[in order for] {a manslayer} to flee there [who] has killed his neighbor {without intent} and was not hating him {previously}, and [so] he could flee to one of these cities {and be safe}.

Numbers 35:6

"All the cities that you will give the Levites will be six cities of refuge, to which the killer can flee; in addition to them you will give forty-two cities.

Numbers 35:11-12

you will select for yourselves cities for your cities of refuge, that a killer who has killed a person unintentionally can flee there.

Numbers 35:15-28

To the {Israelites}, to the alien, and to the temporary resident in their midst there will be these six cities as a refuge to which anyone who unintentionally kills a person may flee.

Deuteronomy 19:1-10

"When Yahweh your God has {exterminated} the nations [concerning whom] Yahweh your God [is] giving to you their land, and you have dispossessed them, and you have settled in their towns and in their houses,

Hebrews 6:18

in order that through two unchangeable things, in which [it is] impossible for God to lie, we who have taken refuge may have powerful encouragement to hold fast 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 Yahweh your God has {exterminated} the nations [concerning whom] Yahweh your God [is] giving to you their land, and you have dispossessed them, and you have settled in their towns and in their houses,
Numbers 35:6
"All the cities that you will give the Levites will be six cities of refuge, to which the killer can flee; in addition to them you will give forty-two cities.
Hebrews 6:18
in order that through two unchangeable things, in which [it is] impossible for God to lie, we who have taken refuge may have powerful encouragement to hold fast to the hope set before [us],