Charles H. Spurgeon on Psalms 71:13

Let them be confounded, etc. By the law of retaliation (talio), he might have said: "Be thou an adversary to their souls, and seek their hurt." Nothing of this is hinted at: his only desire is that they may be confounded and fail, that they may be covered with disgrace and shame. He seeks nothing beyond the frustration of their attempts, that they may begin to be ashamed, and have no cause for boasting that they came off victorious. Musculus.