There is a warrior in a province. As soon as the arrow leaves his hand he cannot retrieve it. Not so, the Holy One Blessed be He. When Israel do not do His will, a decree goes forth from Him, viz. (Devarim 32:41) "When I whet the flash of My sword, etc." But if they repent, immediately he withdraws it, viz. (Ibid.) "My hand shall take hold of justice." I might think that He withdraws it in vain (i.e., unbloodied); it is, therefore, written (Ibid.) "I shall return (with that sword) vengeance to My adversaries." Against whom does He return it? The nations of the world, viz. (Ibid.) "and (with it) My haters shall I repay!"