Numbers 35:20-23

20Now 1if he pushed him in hatred, or he threw something at him 23with malicious intent, and as a result he died, 21or if he struck him with his hand with hostility, and as a result he died, the one who struck him must be put to death; he is a murderer. The blood avenger shall put the murderer to death when he meets him.

22‘4But if he pushed him suddenly, without hostility, or threw any object at him without 5malicious intent, 23or had any 6deadly stone, and without looking he dropped it on him so that he died, while he was not his enemy nor was he seeking 7to harm him,