Kommentar zu Wajikra 20:20

אשר ישכב את דדתו AND IF A MAN SHALL LIE WITH HIS AUNT… [THEY SHALL DIE CHILDLESS] — This verse is intended to teach that the "excision" mentioned above (18:29, where "all these abominations includes the union prohibited in v. 14 of that chapter) consists in their (the offenders’) passing from this world childless.

ערירים ימותו , Heaven will interfere with such couples’ ability to conceive and to give birth to viable children.

That it [involves] the punishment of remaining childless. Explanation: In [parshas] Acharei Mos it is written, after mentioning all the arayos (18:29), “Their souls will be cut off, etc.” This includes the punishment of being childless, because in general, koreis means that he is cut off and his children are cut off. However, I [still] would not know which children are cut off. Are those he had before the sin included in [his] punishment, or specifically those born after the sin, as they were born of a wicked person? Thus the verse [here], “they will die without children,” comes to indicate that they will die childless as they are now [when they sinned, because any children he has from now on will die]. And the [next] verse “They will be without children,” comes to indicate that when they die they will be childless, because if he had children he will bury them, whether he had them before the sin or after the sin, they will all be cut off. Some texts, however, turn it round (Nachalas Yaakov). Re’m raises a question. How can we say that koreis means that he and his seed are cut off? The Gemara (Mo’ed Katan 28a) says in connection with Shmuel the Ramati, that [dying like Shmuel at] 52 years is the death of koreis [which is between 50 and 60 years], and the reason the Gemara did not mention this [in an earlier statement] was due to Shmuel’s honor, since the Holy One had [actually] shortened his years so that he should not witness his sons’ deaths. But why should the Gemara not mention this because of Shmuel’s honor? Since he had sons this could not have been koreis? The answer is that the Tosefta says that [koreis] only applies to small sons who do not have their own merit, and does not apply to adult sons. Therefore, there is no [contrary] proof from Shmuel the Ramati as they were adults.

ערירים — Translate this as the Targum renders it: בלא ולד, childless. Similar is, (Genesis 15:2) "and I will pass away childless (ערירי)”. If he has children he will bury them (i. e. they will die during his life-time); if he has no children when this sin is committed he will die childless (he will beget no children afterwards). That is why Scripture varies the expression in these two verses (this and the following) here stating ערירים ימתו, "they shall die childless", and there ערירים יהיו, "they shall be childless". The expression ערירים ימתו implies: if he has any children at the time he commits the sin, he shall have none remaining when he dies because he will bury them during his lifetime; ערירים יהיו on the other hand, implies: if he has no children at the time when he commits the sin, he shall remain all his life just as he was then (Sifra, Kedoshim, Chapter 12 7; Yevamot 55a).