Rashi on Deuteronomy 32:31/רש"י על דברים ל״ב:ל״א

1כי לא כצורנו צורם FOR THEIR ROCK IS NOT AS OUR ROCK — all this the enemies should have understood, — that it is the Lord who delivered them (the Israelites) into their hands, and the victory is neither theirs nor their god’s, for until now their gods could achieve nothing against our Rock, “for not as our Rock is their Rock”. — The word צור wherever it occurs in Scripture is the equivalent of סלע, rock.

2ואיבינו פלילים AND OUR ENEMIES ARE JUDGES — i.e. are now judges over us; it is evident therefore that our Rock must have delivered us over to them.