The day of the Lord cometh - See Isaiah 13:6.
Cruel - (אכזרי 'akezārı̂y). This does not mean that “God” is cruel, but that the ‘day of Yahweh’ that was coming should be unsparing and destructive to them. It would be the exhibition of “justice,” but not of “cruelty;” and the word stands opposed here to mercy, and means that God would not spare them. The effect would be that the inhabitants of Babylon would be destroyed.
Fierce anger - Hebrew, (חרון אף 'aph chărôn) ‘A glow, or burning of anger.’ The phrase denotes the most intense indignation (compare Numbers 25:4; Numbers 32:14; 1 Samuel 28:18).
To lay the land desolate - Chaldea, Isaiah 13:5.