Exodus 21:13

13 However, if it is not done intentionally, but God lets it happen, they are to flee to a place I will designate.

Read Exodus 21:13 Using Other Translations

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.
But if he did not lie in wait for him, but God let him fall into his hand, then I will appoint for you a place to which he may flee.
But if it was simply an accident permitted by God, I will appoint a place of refuge where the slayer can run for safety.