Negative commandment · Lo Ta’aseh #360 of 613
For a man incapable of procreation not to marry a natural born Jewess
שלא ייקח סריס בת ישראל
The verse · Devarim 23:2
לֹא־יָבֹא פְצוּעַ־דַּכָּא וּכְרוּת שׇׁפְכָה בִּקְהַל ה׳
“He that is wounded in the stones, or has his privy member cut off, shall not enter into the congregation of the Lord.”
The Rambam’s words
For a man incapable of procreation not to marry a natural born Jewess, as [Deuteronomy 23:2] states: "A man with crushed testicles... may not enter [G-d's congregation]."
שלא ייקח סריס בת ישראל, שנאמר "לא יבוא פצוע דכא" (דברים כג,ב).
Who & when
“And this prohibition is practiced in every place and at all times, by males.”
Where in the Mishneh Torah
Hilchot Forbidden Intercourse הלכות איסורי ביאה