If you’re like me and have the reference is to, here’s the relevant verses:
When two men are fighting and the wife of one intervenes to save her husband from the blows of his opponent, if she stretches out her hand and seizes the latter by his private parts,
you shall chop off her hand without pity.
My hunch: it’s God’s saying “Hands off the nards” is always a good policy.
More likely: just another emphasis on the need for women to refrain from getting to close to a man other than her husband.
In response to the direct question of the poster, it’s most likely a law specifically for the Jews that is not binding on Christians today. But “hands off the nards” probably is.