Deuteronomy 19:2
"Thou shalt separate three cities for thee in the midst of thy land, which the LORD thy God giveth thee to possess it."
Cross References (ranked by relevance)
Exodus 21:13
And if a man lie not in wait, but God deliver him into his hand; then I will appoint thee a place whither he shall flee.
Hebrews 6:18
That by two immutable things, in which it was impossible for God to lie, we might have a strong consolation, who have fled for refuge to lay hold upon the hope set before us: