Charles Ellicott Commentary Isaiah 34:6

"The sword of Jehovah is filled with blood, it is made fat with fatness, with the blood of lambs and goats, with the fat of the kidneys of rams; for Jehovah hath a sacrifice in Bozrah, and a great slaughter in the land of Edom." — Isaiah 34:6 (ASV)

The Lord hath a sacrifice in Bozrah ... — Two cities of this name appear in history; one in the Haurân, more or less conspicuous in ecclesiastical history, and the other, of which Isaiah now speaks, in Edom. It was a strongly fortified city, and is named again and again. (Amos 1:12; Jeremiah 49:13; Jeremiah 49:22.) The image both of the sword and the sacrifice appears in Jeremiah 46:10.