I have long time holden my peace - This is the language of Yahweh, and it means that he had for a long time been patient and forbearing; but that now he would go forth as a warrior to overpower and destroy his foes.
I will destroy - The word used here (from נשׁם nâsham) denotes properly to breathe hard, to pant, as a woman in travail; and then to breathe hard in any manner. It here denotes the hard breathing which is indicative of anger, or a purpose to execute vengeance.
And devour at once - Margin, ‘Swallow,’ or ‘Sup up.’ The word שׁאף sha'aph means rather “to breathe hard, to pant, to blow, as in anger, or in the haste of pursuit.” The idea in the verse is, that Yahweh had for a long time restrained his anger against his foes, and had refrained from executing vengeance on them. But now he would rouse his righteous indignation, and go forth to accomplish his purposes in their destruction. All this language is descriptive of a hero or warrior; and is, of course, not to be regarded as applicable literally to God. He often uses the language of people, and speaks of his purposes under the image of human passions. But we are not to infer that the language is literally applicable to him, nor is it to be interpreted too strictly. It means, in general, that God would go forth with a fixed and settled purpose to destroy his foes.