Jamieson, Fausset and Brown on Isaiah 34:8

8. recompenses for the controversy of Zion--that is, the year when God will retaliate on those who have contended with Zion. Her controversy is His. Edom had thought to extend its borders by laying hold of its neighbor's lands and has instigated Babylon to cruelty towards fallen Judah (Psa 137:7; Eze 36:5); therefore Edom shall suffer the same herself (La 4:21, 22). The final winding up of the controversy between God and all enemies of Him and His people is also foreshadowed (Is 61:2; 63:4; 66:14-16; Mal 4:1, 3; 2Th 1:7, 8, 9; Re 11:18; 18:20; 19:2).