LEV782 It is a positive commandment to rise up before an aged man, and to honor a Torah scholar, getting up before him as Scripture says, You shall rise before a sevah, a man of hoary head, and honor the presence of zaken, an old man [this verse]. The term sevah "a man of hoary head") means someone of very advanced age, even if he is not a man of wisdom. One is duty-bound to stand before him – – even a wise scholar who is very young; but he is not obligated to stand up to his full height before him [the old man], but only enough to honor him. The term zaken means zeh she-kanah hochmah, one who has acquired wisdom. Even if he is very young, one is to stand up to his full height before him, from the time he [the scholar] comes within four cubits until he has left his presence. One is likewise duty-bound to give honor to his Torah teacher, even if he has not learned most of his knowledge [of Torah] from him. If a Torah a teacher is willing to overlook his honor, it may be left aside. But it is a great wrong to disparage or disgrace Torah scholars, or to hate them. Whoever disgraces such scholars will have no share in the world-to-come.