The Gemara cites other expositions that deal with Torah study. Rabbi Ḥama, son of Rabbi Ḥanina, said: What is the meaning of that which is written: “Iron sharpens iron, so a man sharpens the countenance of his friend” (Proverbs 27:17)? This verse comes to tell you that just as with these iron implements, one sharpens the other when they are rubbed against each other, so too, when Torah scholars study together, they sharpen one another in halakha. Rabba bar bar Ḥana said: Why are matters of Torah compared to fire, as it is stated: “Is not My word like fire, says the Lord” (Jeremiah 23:29)? To tell you: Just as fire does not ignite in a lone stick of wood but in a pile of kindling, so too, matters of Torah are not retained and understood properly by a lone scholar who studies by himself, but by a group of Sages.
אמר רבי ירמיה אמר רבי שמעון בן לקיש שני תלמידי חכמים הנוחין זה לזה בהלכה הקדוש ברוך הוא מקשיב להן שנאמר אז נדברו יראי ה׳ וגו׳ אין דבור אלא נחת ... אמר רבי אבא אמר רבי שמעון בן לקיש שני תלמידי חכמים המקשיבים זה לזה בהלכה הקדוש ברוך הוא שומע לקולן שנאמר היושבת בגנים חברים מקשיבים לקולך השמיעני ואם אין עושין כן גורמין לשכינה שמסתלקת מישראל שנאמר ברח דודי ודמה וגו׳
Rabbi Yirmeya said that Rabbi Shimon ben Lakish said: Two Torah scholars who are agreeable to each other when engaging in discussions of halakha, the Holy One, Blessed be He, listens to them, as it is stated: “Then they that feared the Lord spoke [nidberu] one with another; and the Lord hearkened, and heard, and a book of remembrance was written before Him, for them that feared the Lord, and that thought upon His name” (Malachi 3:16). And the term speech [dibbur] means nothing other than calm ... Rabbi Abba said that Rabbi Shimon ben Lakish said: Two Torah scholars who listen to each other in the discussion of halakha, the Holy One, Blessed be He, hears their voice, as it is stated: “You who dwell in gardens, the companions heed your voice, cause me to hear it” (Song of Songs 8:13). And if they do not do so, i.e., they do not listen to each other, they cause the Divine Presence to depart from among Israel, as it is stated in the following verse: “Run away, my beloved, and be like a gazelle or a young hart upon the mountains of spices” (Song of Songs 8:14).
The Gemara asks: What is the meaning of the phrase “enemies in the gate” with regard to Torah study? Rabbi Ḥiyya bar Abba says: Even a father and his son, or a rabbi and his student, who are engaged in Torah together in one gate become enemies with each other due to the intensity of their studies. But they do not leave there until they love each other, as it is stated in the verse discussing the places the Jewish people engaged in battle in the wilderness: “Therefore it is said in the book of the wars of the Lord, Vahev in Suphah [beSufa], and the valleys of Arnon” (Numbers 21:14). The word “vahev” is interpreted as related to the word for love, ahava. Additionally, do not read this as “in Suphah [beSufa]”; rather, read it as “at its end [besofa],” i.e., at the conclusion of their dispute they are beloved to each other.
וְכָל אָדָם יָכוֹל לְקַיֵּם זֹאת, לְהַעֲמִיד תַּלְמִידִים. כִּי כְּשֶׁשְּׁנַיִם מְדַבְּרִים יַחַד בְּיִרְאַת שָׁמַיִם, אֲזַי כְּשֶׁאֶחָד מֵאִיר לַחֲבֵרוֹ בְּאֵיזֶה דִבּוּר, נֶחֱשָׁב חֲבֵרוֹ אֶצְלוֹ בְּחִינַת תַּלְמִיד. וְלִפְעָמִים נַעֲשֶׂה לְהֶפֶךְ, דְּהַיְנוּ כְּשֶׁאַחַר־כָּךְ הוּא מְקַבֵּל מֵחֲבֵרוֹ אֵיזֶה דִבּוּר, אֲזַי נַעֲשֶׂה הוּא בִּבְחִינַת תַּלְמִיד לְגַבֵּי חֲבֵרוֹ. וְצָרִיךְ כָּל אָדָם לִזָּהֵר, לְהִשְׁתַּדֵּל וְלַעֲסֹק בָּזֶה, כִּי לֹא תֹהוּ בְרָאָהּ לָשֶׁבֶת יְצָרָהּ (ישעיה מה), כִּי צָרִיךְ כָּל אֶחָד לַעֲסֹק בְּיִשּׁוּבוֹ שֶׁל עוֹלָם, שֶׁיִּהְיֶה הָעוֹלָם מְמֻלָּא מִבְּנֵי אָדָם, כְּמוֹ שֶׁכָּתוּב (בראשית א): וּמִלְאוּ אֶת הָאָרֶץ, כִּי זֶה עִקָּר יִשּׁוּב הָעוֹלָם, כְּשֶׁהָעוֹלָם מְמֻלָּא מִבְּנֵי אָדָם, הַיְנוּ מִבְּנֵי דֵּעָה.
And every person can raise great students! For when two people are conversing together about their relationships with God, then when one of them illuminates/makes something shine for his companion in something he says, then his companion is considered at that moment like a student. And sometimes it is the opposite – that later the first one will receive from his friend some word that shines, and then he will become like a student of his companion. And every person must dedicate time and effort to occupy themselves in this (raising students), for “God did not create the world to be chaos, rather for it to be populated” (Isaiah 45) – for every person must populate the world, that it should be full of human beings, as it is written “fill the earth” (Genesis 1) – for this is the essential act of populating the world: when it is full of human beings, i.e. full of people of knowledge.