Where does “διάβολος” come from?

διάβολος (Ancient Greek) comes from Ancient Greek διαβάλλω, from Ancient Greek δῐᾰ-, from Ancient Greek διά, from Proto-Indo-European dwís, from Proto-Indo-European dwóh₁ — two.

διάβολος (Ancient Greek): slanderous; libellous; slanderer; the Devil