It is not permissible for the principal, teachers, or anyone to (Part No. 26; Page No. 120)
deliberately cause the failure of a student or incite others to do that or reduce her rightful grades for oral or written exams, for the injustice it entails. Allah (Glorified and Exalted be He) prohibited injustice as mentioned in the Hadith Qudsy (Revelation from Allah in the Prophet's words),
O My slaves, I have forbidden wrongdoing for Myself and I have made it Haram (prohibited) among you, so do not wrong one another.
Whoever has done this should repent and seek Allah's Forgiveness for what has happened.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.