In light of the following posts (Lazer Brody: Beating the Porn addiction & The War of Kedusha) I decided to write up an abstract from the Nishmat Avraham on this topic. It is a fantastic set of seforim translated from the original Hebrew into English and is published by Artscroll
(Abstract from Nishmat Avraham Even Haezer [Artscroll] Pg 110 – Pg 112, Pg 118)
Even Haezer Siman 23: The sin of Wasting Sperm
1) It is forbidden to emit sperm to waste and this sin is greater than any other sin of the Torah. Thereby a man many not perform coitus interruptus nor may he may he marry a girl too young to have children
3) It is forbidden for a man to cause self-erection or to think erotic thoughts. If such thoughts do come to him he should discard them for Torah thoughts since the Torah is liken to a “beloved hind inspiring favor” Thus it is forbidden for a man to sleep flat on his back, but he should turn slightly to one side to prevent him having an erection. He must not look at male and female animals or birds that are copulating. If his work is breeding animals he may manually help them in the process since he is then occupied with his work and will not come to erotic thoughts
The Maggid Mishneh writes that the source of this halacha is Gemera (Niddah 13A). Rebbe Yochana said: He who emits sperm to waste is punishable by death as the verse says (Bereishit 38:10:” And what he did (coitus interruptus – spilling the sperm outside) was evil in the eyes of Hashem and for this he too died” The Levush (Bereishit 38:10) writes that it is forbidden to emit sperm to waste and that this sin is very great since sperm was created in man for the specific purpose of inhabiting the earth, as the verse says (Isiah 45:18) “Hashem did not create the earth for emptiness; He fashioned it to be inhabited.” And when one emits sperm to waste it is as if he destroys the earth. This is what the generation of the flood did as it says of them (Bereishit 6:12) “For all flesh had corrupted its way upon the earth,” that is, they destroyed their sperm (the interpretation is based on the the Hebrew word corrupted which has the same root as the word to destroy – author)… There are many verses which teach us this as a basic halachah and not merely as a homiletic exegesis. This was the sin of Onen with Tamar, and it was for this that he died (end of quote from the Levush)
The Aruch Laner (Niddah 13B) and the Binyan Tzion (Sh”T Siman 135) writes that perhaps the admonition not to destroy ones sperm comes either from the verse (Deverim 20:19) “Do not destroy its trees,” a general commandment which includes harming oneself, or perhaps it is a halachah that was taught to Moshe Rabbeinu at Sinai.
Rav Auerbach zt”l wrote to me that the basis for the prohibition of emitting sperm to waste requires further study; for if a mans status was a matter of doubt in that the might be either a Cohen or a mamzer he cannot marry (If he is a mamzer he can only marry a mamzeret or a giyoret; on the other hand if he is a Cohen he can neither marry a mazeret nor a giyoret – author). Since he would not be able to fulfill the mitzvah: “He fashioned it to be inhabited,” would he be permitted to emit his sperm to waste? The statement of the Aruch LaNer that this is part of the general commandment prohibiting destruction also requires further study. For cutting down a tree or harming oneself is permissible if it is done for one’s benefit. On the other hand, if the prohibition is a halacha that was taught to Moshe Rabbeinu at Sinai, then one may not rule leniently in any circumstance, even if the sperm was emitted for medical reasons in order to fulfill the mitzvah of “Be fruitful and multiply” (end of quote from Rav Auerebach zt”l)
The Pnei Yehoshua (SH”T Pnei Yehoshua Even Haezer Chelek Beis, Siman 44) writes that the prohibition of emitting sperm to waste is not included in the prohibition of gilui arayot or of murder. For although Chazal have stated that if one does so it as if he has committed murder, they meant to emphasize that the sin was as great as sin of murder. And, when they compared it to sin of gilui arayot they meant that this was at a Rabbinic Level, for the Rambam (Issurei Biah 21:18) writes of this sin and does not rule that one is flogged for it in the way that he writes of the other acts enumerated there. Moreover, he does not even write the person is given Rabbinically ordained lashes, only that he is excommunicated. Rabbeinu Tam (Tosfot Niddah 13B) also writes that when the Gemara says that one who willfully causes an erection should be a in of state of excommunication, it means that Beit Din should excommunicate him. If this was forbidden by Torah Law, why should the Gemara need to tell us that he excommunicated; even one who transgresses Rabbinic Law is excommunicated.
Rav Aurebach zt”l wrote to me wondering why ones punishment for emitting sperm to waste should be flogging; if we compare it to adultery, it should be punishable by death. He also noted that excommunication for causing erection only is an innovative ruling.
The Torat Chesed (SH”T Chelek Beis, Siman 33) writes that whether emitting sperm to waste is forbidden by Torah or Rabbinic law is a subject of debate among the Rishonim. It would appear that the Tosafot (Sandhedrin 59B) believe that it is forbidden by Torah Law. However, the Meshivat Nefesh disagrees, writing that it cannot be forbidden by Torah Law. But the Mishnah LaMelech (Laws of Kings, 10:7) also questioned the Tosafots opinion and gives an answer. Since the opinion of Tosafot is no longer under question, it would appear that emitting sperm to waste is forbidden by the Torah and the prohibition is included with the overall mitzvah of procreation, The Torat Chessed, however, proves that the Ramban and the Meshivat Nefesh believes that it is only forbidden by Rabbinic Law and not a prohibition by Torah Law (See Otzar Haposkim Daf 83A)
Rav Auerebach zt”l wrote to me that the concept of including the sin of emitting sperm to waste within the framework of the overall mitzvah to procreate is very difficult to accept. For if this were true, then if the husband travels abroad or his wife is old or has a had a hysterectomy, it should be permissible for him to waste sperm (that is, since he cannot keep the mitzvah of procreation, he would be permitted to waste his sperm, this cannot be – author) (end of quote from Rav Auerebach zt”l)
The Igrot Moshe (Even Haezer Chelek 3 Siman 14) writes, perish the though that the one should think that emitting sperm to waste is only forbidden by Rabbinic law. Emitting sperm to waste is forbidden by Torah law and is punishable by death by Heaven, as Rebbe Yochanan states (Niddah 13A). It is such a terrible sin that he Shulchan Aruach writes that it is the most severe of all Torah forbidden sins. And even though this is not to be taken literally, for the sexual act with a married woman or a woman who is niddah are very severe sins as stated by the Beit Shmuel, nevertheless the Shulchan Aruch would not have used such strong language if wasting sperm were only a Rabbinically forbidden. For Rebbe Pinchas ben Yair (Ketuvot 45A) derived the prohibition of thinking unseemly thoughts, from the verse “You shall guard against anything evil”, explaining that this was so that he would not have a nocturnal emission. And Tosafot state (Avodah Zara 20b) that this was to be thought of as a true understanding of the verse (which would give the prohibition Torah status – author) Certainly then, the act of emitting sperm to waste is included in this negative commandment. That it is not to to be found in the Rambam’s list of negative commandments does not prove that it is not forbidden by the Torah, for there are many Torah prohibitions which are not included in this list. Perhaps this is because the Torah only states that is punishable by death but not that it is forbidden to do so (the three hundred and sixty-five negative commandments listed by the Rambam each have two separate verses in the Torah, one stating that it is forbidden, and the other, the punishment for its transgression – author). The negative commandment: “You shall guard against anything evil,” includes other forbidden acts in addition to unseemly thoughts and therefore the Rambam did not wish to number it as separate negative commandment; see Sefer HaMitzvot that the Ramban did count it as a separate commandment, mitvah number 11 (end of quote from the Igrot Moshe)