The 209th mitzvah is that we are commanded to honor the Sages1 and to stand up before them as a sign of respect.
The source of this commandment is G‑d's statement (exalted be He),2 "Stand up before the elderly, and give respect to the old."(The Oral Torah understands the word "old" in this context as meaning those with great wisdom and learning, although we must also honor those who are old literally-J.S.)
The Sifra3 says, "The words, 'stand up' and 'give respect' [when taken together] teach you to stand up when it shows respect."4
The details of this mitzvah have been explained in the first chapter of Kidushin.5
You should be aware that although this is a general obligation on everyone to honor the Sages, and even one Sage to another equal to him in stature, as explained in the statement,6 "The Sages in Bavel stand up one before the other"; nevertheless there is a special additional requirement for a student, i.e. that the honor that a student must show his teacher is much greater than the honor he must show another Sage.
In addition to honoring your teacher you must revere7 him, since it is already explained that your obligation to your teacher is even greater than that to your father, whom Scripture obligates you to honor and revere.8 Our Sages said explicitly,9 "Between [honoring] his father and his teacher, his teacher comes first."
The Sages have already explained10 that it is forbidden for a student to dispute his teacher, i.e. to reject his authority, to give separate interpretations, and to teach or issue rulings without his permission. It is forbidden for him to argue with him, or speak angrily to him, or to judge him harshly, i.e. to give any kind of [non-literal11] explanation to his action or speech, since it is possible that this was not his intention.
Our Sages said in the Talmudic chapter "HaChelek",12 "Anyone who goes against his teacher is as if he went against the Divine Presence., as it is written13 [regarding Korach], 'when they rebelled against G‑d,'"; "Anyone who makes a dispute against his teacher is as if he made a dispute against the Divine Presence, as it is written,14 'These are the Waters of Dispute where the Israelites disputed with G‑d'"; "Anyone who speaks against his teacher is as if he speaks against the Divine Presence, as it is written,15 'Your complaints are not against us but against G‑d'"; and "Anyone who has second thoughts about his teacher is as if he had second thoughts about the Divine Presence, as it is written,16 'The people spoke out against G‑d and Moses.'" All this is clear, since the rebellion of Korach, and the dispute, complaints and wicked thoughts17 of the Jewish people were against Moses, leader of the entire Jewish people, yet Scripture considers each of them to have been committed against G‑d. Our Sages said explicitly,18 "You should fear your teacher as you fear G‑d."
All this19 is derived from the Scripture's command of honoring our Sages and our parents, rather than counting as a separate commandment,20 as explained in the Talmudic text.