14 Thou therefore, O God, that will not march forth in our powers, “Give to us aid from tribulation, and vain is the safety of man”. Go now they that salt have not, and desire safety temporal for their friends, which is empty oldness. “Give to us aid:” from thence whence You were supposed to forsake, thence succour. “In God we will do valour, and Himself to nothing shall bring down our enemies”. We will not do valour with the sword, not with horses, not with breastplates, not with shields, not in the mightiness of an army, not abroad.
But where? Within, where we are not seen. Where within? “In God we will do virtue:” and as if abjects, and as if trodden down, men as if of no consideration we shall be, but “Himself to nothing shall bring down our enemies.” In a word, this thing has been done to our enemies. Trodden down have been the Martyrs: by suffering, by enduring, by persevering even unto the end, in God they have done valour. Himself also has done that which follows: to nothing He has brought down the enemies of them. Where are now the enemies of the Martyrs, except perchance that now drunken men with their cups do persecute those whom at that time frenzied men did use with stones to persecute?
Source: The Enarrations, or Expositions, on the Psalms (New Advent)