27 “You have heard that it was said, ‘Do not commit adultery.’ 28 But I say to you that whoever looks at a woman to desire her has already committed adultery with her in his heart. 29 If your right eye causes you to sin, tear it out and throw it away! It is better to lose one of your members than to have your whole body thrown into hell. 30 If your right hand causes you to sin, cut it off and throw it away! It is better to lose one of your members than to have your whole body go into hell.
The Gemara suggests: Come and hear, as it is taught in a baraita that Rabbi Tarfon says: If one’s hand goes to his penis, his hand should be severed upon his navel. The Rabbis said to him: If so, in a case where a thorn was stuck in one’s belly, should he not remove it? Rabbi Tarfon said to them: Indeed, he should not remove it, and if he does so his hand should be severed. The Rabbis replied: But if his hand is severed while it is upon his navel, won’t his belly be split open? Rabbi Tarfon said to them: It is preferable that the belly of one who acts in this manner should be split open, and he should not descend into the pit of destruction.