7. Their sin had been accumulating from age to age until God at last repaid it in full.
mountains—(Isa 57:7; Eze 18:6; 20:27, 28; Ho 4:13).
their—"Your" had preceded. From speaking to, He speaks of them; this implies growing alienation from them and greater distance.
work—the full recompense of their work (so Isa 49:4).