Deuteronomy 4:42

For the slayer to flee there when he shall slay his friend without knowledge; and he hated him not yesterday the third day; and he fled to one of these cities and he lived:

Numbers 35:6

And the cities which ye shall give to the Levites, six cities of refuge, which ye shall give to flee there to the slayer: and upon them ye shall give forty and two

Numbers 35:11-12

And build ye to you cities; cities of refuge shall they be to you; and the slayer to flee there smiting a soul in error.

Numbers 35:15-28

For the sons of Israel and for the stranger, and for the sojourner in the midst of you shall be six cities: these for refuge to flee there all smiting a soul in error.

Deuteronomy 19:1-10

When Jehovah thy God shall cut off the nations which Jehovah thy God gave to thee their land, and thou didst possess and dwell in their cities, and in their houses;

Hebrews 6:18

That by two unalterable deeds, in which it is impossible for God to deceive we might have a strong consolation, taking refuge in holding firmly the hope set before:

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 Jehovah thy God shall cut off the nations which Jehovah thy God gave to thee their land, and thou didst possess and dwell in their cities, and in their houses;
Numbers 35:6
And the cities which ye shall give to the Levites, six cities of refuge, which ye shall give to flee there to the slayer: and upon them ye shall give forty and two
Hebrews 6:18
That by two unalterable deeds, in which it is impossible for God to deceive we might have a strong consolation, taking refuge in holding firmly the hope set before: