John Wesley on Deuteronomy 32:13

The high places - To conquer their strongest holds, which often are in the mountains, and their cities fenced with walls of greatest height and strength. To ride upon, in scripture phrase, is to subdue or conquer. Out of the rock - This being a land flowing with honey, where the bees made honey in the holes of rocks, or in the trees that grew upon or among the rocks. Out of the flinty rocks - The olive - trees grow and bear most fruit in rocky or hilly places.