Deuteronomy 19:4

19:4 Now this is the law pertaining to one who flees there in order to live, if he has accidentally killed another without hating him at the time of the accident.

Deuteronomy 19:10-11

19:10 You must not shed innocent blood in your land that the Lord your God is giving you as an inheritance, for that would make you guilty. 19:11 However, suppose a person hates someone else and stalks him, attacks him, kills him, and then flees to one of these cities.