Naradasmriti m1.48

m1.48

nābhiyukto 'bhiyuñjīta tam atīrtvārtham anyataḥ /
na cābhiyuktam anyena na viddhaṃ veddhum arhati //

One accused of an offence must not lodge a plaint himself, unless he have refuted the charge raised by the other party. Neither (is he allowed to accuse) one who has already been accused by a different party. It is wrong to strike one again who has already been struck (by another).