The sages found an internal contradiction in the verse “None who go to her return, nor do they regain the paths of life” (Proverbs 2:19), that any who walk the paths of heresy and apostasy will not succeed in returning nor achieve longevity. The sages asked: If they do not repent from their heresy and apostasy, how could they achieve longevity?
Answer: The verse should be interpreted to mean that if one repents of his heresy, his path to repentance will be very difficult, and if he in any case succeeds in repenting, he will not live long; he will die in sorrow over the difficulty of repentance.
The scholars asked: If so, if one who repents his heresy and apostasy will die, how did it happen that one woman came before the sage Rav Chisda and told him that one of the lesser prohibitions which she had transgressed was having sexual relations with her son, from which a child was born, and that she now wised to repent for the incest to which she had become accustomed? The sage told her to repent, but that she should know that her repentance would cause her death. She repented her wicked ways, but did not die. Answer: She did not fully repent.

(Talmudic discourses which were passed down orally between the sages naturally underwent changes and became subject to inaccuracies. Often we find alternate versions of the same discussion. In the Talmud these alternate versions begin “And some say…”)

And some say the above discussion should go like this: What can be concluded from the sages’ interpretation of the verse above is that a person who repents of apostasy will die, but one who repents from adultery will not die. The scholars asked: There was an incident in which a woman who came to the sage Rav Chisda and told him that she had had sex with her grown son and that she had born him a child. She now wished to repent. The sage told her to repent, but that she should know that if she did so, she would die, and this is what happened. This means that even one who repents from adultery dies, not only those who repent from apostasy. Answer: This woman not only transgressed laws of sexual propriety, she also was a total apostate; her death was caused by her repentance from heresy.
The scholars went on to ask: If so, if repentance from heresy is so difficult and causes death but repentance from sexual transgressions, which are less severe transgressions, does not cause death, how did it happen that one of the sages gave up his sexual misconduct and therefore died? The incident was as follows: R’ Elazar the son of Dordia went to a top prostitute, one who commanded a high fee for her services, and in the middle of their sexual act she expelled gas and said, “Just as this gas cannot return from whence it came, so will R’ Elazar the son of Dordia never be taken back in repentance.” Her words struck his heart and he decided to repent for his sexual misconduct. He sat and placed his head between his knees and wept until he died. This means that even one who repents for sexual misconduct will in the end die. Answer: Since R’ Elazar the son of Dordia was addicted to sex and licentiousness, his repentance was like the repentance of one who is addicted to his heresy, and so he died.
(Babylonian Talmud, Tractate Avodah Zarah 17a)