What is the ruling of Islamic Sharia on some mothers cutting above their daughter's knee to prevent any aggressor from reaching her, believing that this preserves her virginity?

This act is objectionable and a baseless superstition. It is not permissible to perform it and it must be abandoned and guarded against. The claim that it preserves a girl's virginity is a false assertion, inspired by Satan, with no basis in Islamic law. Scholars must clarify this and warn against it.