Joshua 20:3 - Joseph Benson’s Commentary on the Old and New Testaments

Unwittingly Hebrew, Through ignorance, or error, or mistake, and without knowledge. The same thing is twice repeated, to cut off all expectations that wilful murderers might have of protection here. God having declared that such should be taken even from his altar, that they might be killed. It is strange that any Christians should make their sanctuaries give protection to such persons whom God hath so expressly excepted from it! Avenger The nearest kinsman, who had right or power to demand or take vengeance for the slaughter.