Sanhedrin 69A

ואמר רחמנא: ״איש״. איש ⁠– אתה צריך לחזור עליו אם יש לו גואלין ואם לאו. קטן ⁠– אי אתה צריך לחזור עליו, בידוע שאין לו גואלין.

And God states: “But if the man has no relative,” teaching that it is only in the case of a convert who is a man that you must go around seeking whether or not he has relatives, i.e., children who were born to him after his conversion. But in the case of a convert who is a minor, you do not have to go around searching for relatives; it is known that he has no relative, since a minor cannot father a child.

איתיביה אביי: ״איש״⁠ – אין לי אלא איש. בן תשע שנים ויום אחד שראוי לביאה מניין? תלמוד לומר: ״ואיש״.

Abaye raised an objection to Rabba from a baraita discussing a designated female slave, about whom the verse states: “And if a man lies carnally with a woman who is a female slave designated to a man, and not fully redeemed, nor freedom given her, inquiry should be made; they should not be put to death, because she was not free” (Leviticus 19:20). From the word “man,” I have derived only that this halakha applies to an adult man. But as for a minor aged 9 years and one day, who is fit for having sex, from where is it derived that he too is subject to this halakha? The verse states: “And if a man.” The extraneous letter vav, meaning “and,” serves to include a minor who is 9 years old, as already at that age he can perform complete sex.

אמר ליה: יש לו ואינו מוליד, כתבואה שלא הביאה שליש דמי.

Rabba said to Abaye: There is no proof from here, as even though a 9-year-old boy has sperm, he cannot father a child. His sperm is like the seed of grain that was cut even though it had not yet reached 1/3rd of its growth. Such seed, even if planted, will not grow.