Charles H. Spurgeon on Psalms 56:9

(first clause). It was somewhat that when David prayed he was saved from his enemies. "I will call on the Lord: so shall I be saved from mine enemies" (2Sa 22:4); there is the defensive power of prayer; but it is more that it puts enemies to the foil. When I cry unto thee, then shall mine enemies turn back and be put to flight; there is the offensive power of prayer. In David's tower there was an armoury, thalpijoth, a place to hang swords with two edges, swords with two mouths (Canticles 4:4); a defensive and an offensive edge. Both edges must be used by such as seek safety. Prayer is a sword with two edges. "Put up thy sword into his place, "says Christ to Peter: "for all they that take the sword shall perish with the sword." Mt 22:52. But he that takes not this sword may happen to perish by the sword; and the drawing of this sword may save a man from perishing by the sword. Mark that last reason that our Saviour adds why Peter should put up his sword: "Thinkest thou that I cannot now pray to my Father, and he shall presently give me more than twelve legions of angels?" (Mt 22:53). As if he had said, If it were my mind to confound these mine enemies that now set upon me, I should not need thy sword to do it. I could pray to my Father, and could presently by prayer bring such forces into the field as should rout and scatter all mine enemies; hereby implying, that if he would, he could do his enemies more damage and mischief by his prayers against them than by the sword and all instruments of war. Prayer is twelve legions strong, yea, twelve legions of angels strong against enemies. Jeremiah Dyke (1620), in the Righteous Man's Tower.