Sanhedrin 92A

יקבהו לאום״, ואין לאום אלא עוברין, שנאמר: ״ולאם מלאם יאמץ״. ואין קבה אלא קללה, שנאמר: ״מה אקב לא קבה אל״. ואין בר אלא תורה, שנאמר: ״נשקו בר פן יאנף״.

the people [leom] should curse him [yikkevuhu], but blessing should be upon the head of one who provides” (Proverbs 11:26). And the term leom is referring to nothing other than fetuses, as it is stated: “Two nations are in your womb, and two peoples should be separated from your bowels; and the one leom should overcome the other leom” (Genesis 25:23). And kabbo is referring to nothing other than curse, as it is stated in the statement of Balaam: “How can I curse one who is not cursed [kabbo] by God?” (Numbers 23:8). And bar is referring to nothing other than Torah, as it is stated: “Pay homage to bar lest He be angry” (Psalms 2:12), i.e., observe the Torah to avoid God’s anger.

עולא בר ישמעאל אומר: מנקבין אותו ככברה. כתיב הכא: ״יקבהו לאום״, וכתיב התם: ״ויקב חר בדלתו״. ואמר אביי: כי אוכלא דקצרי.

Ulla bar Yishmael says: One perforates like a sieve a person who withholds halakha from a student. It is written here: “He who withholds bar, the people yikkevuhu” (Proverbs 11:26), and it is written there: “And he bored [vayyikkov] a hole in its lid of it” (II Kings 12:10). And Abaye says: One perforates him like a launderers’ utensil used for sprinkling water on garments.

ואם למדו, מה שכרו? אמר רבא אמר רב ששת: זוכה לברכות כיוסף, שנאמר: ״וברכה לראש משביר״. ואין משביר אלא יוסף, שנאמר: ״ויוסף הוא [השליט על הארץ הוא] המשביר לכל עם הארץ״.

And if one teaches the student halakha rather than withholding it, what is his reward? Rava says that Rav Sheshet says: He is privileged to receive blessings like Joseph, as it is stated at the end of that verse: “But blessing should be upon the head of one who provides [mashbir]” (Proverbs 11:26). And mashbir is referring to no one other than Joseph, as it is stated: “And Joseph was the governor of the land, and he was the provider [hamashbir] to all the people of the land” (Genesis 42:6).