כִּֽי־יִנָּצ֨וּ אֲנָשִׁ֤ים יַחְדָּו֙ אִ֣ישׁ וְאָחִ֔יו וְקָֽרְבָה֙ אֵ֣שֶׁת הָֽאֶחָ֔ד לְהַצִּ֥יל אֶת־אִישָׁ֖הּ מִיַּ֣ד מַכֵּ֑הוּ וְשָׁלְחָ֣ה יָדָ֔הּ וְהֶחֱזִ֖יקָה בִּמְבֻשָֽׁיו׃
When men strive together one with another, and the wife of the one draweth near to deliver her husband out of the hand of him that smiteth him, and putteth forth her hand, and taketh him by the secrets;
The Five Books of Moses, by Everett Fox
In a law literally protecting maleness, a wife loses her hand over an act understood by a patriarchal society to be completely intolerable. Not even the close ties of a woman to the males of her family may overrule this (Frymer-Kensky 1992a). But also at issue may be the idea that the convenant is passed on biologically, and hence damaging the genitals damages the covenant (Greenstein, personal communication).