Rashi, like his predecessors, saw a link between two meanings of morim: rebels and teachers. He used both in one sentence when he said that the worst type of rebels are those who turn against their teachers.
In Yiddish one of the words for a teacher is rebbe or its diminutive form rebbele, so we could derive from his comment the admonition, “Don’t rebel against your rebbele!”
More seriously, we wonder what impels anyone to turn against their teacher. Sometimes an incompetent or insensitive teacher can turn a pupil off a subject of study, even Judaism as a whole. Sometimes the problem is not the teacher but the pupil.
King Solomon asks, Ra’ita ish chacham b’einav? – “Have you seen a person who is wise in his own eyes? There is more hope for a fool than for him” (Prov. 26:12). A fool can always be taught; someone who is wise in his own eyes is too conceited to be able to learn or to improve himself.
Every teacher dreams of the day when a pupil will be able to leave the nest and make his/her own way in the world, but that kind of pupil will never forget the grounding the teacher has given. But a pupil who is only too ready to forget the teacher is probably already too wise in his/her own eyes.