הלכה על דברים 23:1

That a eunuch not marry a daughter of Israel: That one whose sexual organs were damaged by the blow of a person or an animal or a tree - meaning to say, not at the hands of the Heavens - to the point that he cannot reproduce is prevented from marrying a daughter of Israel. And about this is it stated (Deuteronomy 23:1), "No one whose testes are crushed or whose member is cut off shall come into the congregation of the Lord."