It is reported that Mujāhid – Allāh have mercy on him – said, “The teacher of the kuttāb (where the children would be taught, the madrasah) will be brought on the Day of Resurrection, and if he was not fair and just with the boys, he will be grouped with the tyrants.”
Abū Bakr Al-Daynūrī, Al-Mujālasah wa Jawāhir Al-‘Ilm article 619.