Musar for Nedarim 64:1

What do we mean by repentance in which one builds a fence between himself and his temptation? A man should not look at the laughing amusements of matrons and virgins and he should not look directly in the face of a woman or between her breasts, and not even at his own wife before she has immersed herself after the period of prohibition. And thus should he make a fence around all the commandments. And our teacher, Abraham ben David, of blessed memory, wrote: "And we have seen in connection with our Sages that they were completely pious men and they used to build many fences to protect themselves from temptation. And there was among them even one who separated himself from his wife after he had fulfilled the commandment of "Be fruitful and multiply!" And each of them would fence himself off from temptation according to the manner of man he knew himself to be. For there is a man who has a lust to commit one sin but not another. For example, one may have a desire to commit fornication but not to steal, and another may have the lust to steal but not to commit the sin of fornication. Therefore every one must make fences according to what he sees in himself, against those temptations wherein his evil inclination is gaining strength. If his mind is drawn to theft, let him refrain from receiving pledges in trust or from managing the property of others. And thus must one make fences for everything wherein he is tempted. And thus our Sages said concerning Abraham, that his desire made peace with him (Gen. Rabbah 54a). And concerning this it is said, "When a man's ways please the Lord, He maketh even his enemies to be at peace with him" (Prov. 16:7). And King David waged war against his desire, and when he saw that his desire was not mild and his nature gentle, and when he realized that he could not overcome it, he stood up and slew it, as it is said, "And my heart is wounded within me" (Ps. 109:22). And the meaning of it is that Abraham had a desire that was gentle, and his nature was easy and pleasant, and it was not necessary for him to wage war against it. As they said (Nedarim 32b): At first, the Holy One, Blessed be He, caused Abraham to rule over two hundred and forty-three limbs. But later God caused him to rule over two hundred and forty-eight limbs, by giving him dominion over his two eyes, his two ears, and his membrum (i.e., because of his willingness to undergo circumcision, he achieved complete control over any sex impluse). But as for David, his desire was always hard and strong, and he had to wage war against it every day, and when he saw that he could not withstand it, he arose up against his evil desire and slew it. There are those who say that David slew his desire by fasting, and there are those who say he kept away from women altogether, for he feared lest that which was permitted might seduce him into doing something that was forbidden. Whichever version is correct (they both agree that) after David saw that his desire was gaining mastery over him, he set himself to make it yield, to fight against it, until he succeeded in subduing it.