Adam Clarke on Deuteronomy 32:36

The Lord shall judge his people - He has an absolute right over them as their Creator, and authority to punish them for their rebellions as their Sovereign; yet he will repent himself - he will change his manner of conduct towards them, when he seeth that their power is gone - when they are entirely subjugated by their adversaries, so that their political power is entirely destroyed; and there is none shut up or left - not one strong place untaken, and not one family left, all being carried into captivity, or scattered into strange lands. Or, he will do justice to his people, and avenge them of their adversaries; see Deu 32:35.