Charles Ellicott Commentary Nahum 1:2

"Jehovah is a jealous God and avengeth; Jehovah avengeth and is full of wrath; Jehovah taketh vengeance on his adversaries, and he reserveth [wrath] for his enemies." — Nahum 1:2 (ASV)

God ... furious. —Better, A jealous and vengeful God is Jehovah, an avenger is Jehovah, indeed, wrathful. This verse lays the groundwork for the declaration of God’s sentence against the offending city. There are, of course, several passages in the Law which attribute the same character to Jehovah, for example, Exodus 20:5; Deuteronomy 4:24. Nahum’s model, however, is a passage of opposite meaning, the well-known proclamation of Jehovah’s attribute of mercy (Exodus 34:6–7). To that passage the present is a kind of counterpoise, Êl kannô v’ nôkêm here being the counterpart to Êl rachoom v’ channoon there.