It is narrated from Muhammad bin Sirin (may Allah have mercy on him) that I asked about the writing of a teacher, so he said: There was a teacher in Madinah, the children of prominent people used to study with him, he was a slave, his masters would demand some work from him, so the children would say: Let us do it, but he would prevent them from doing so.
Hadith Referenceسنن سعید بن منصور / كتاب التفسير / 125