Mishneh Torah — Transmission of the Oral Law מסירת תורה שבעל פה, Chapter 37

וּשְׁאֵלוֹת רַבּוֹת שׁוֹאֲלִין אַנְשֵׁי כָּל עִיר וְעִיר לְכָל גָּאוֹן שֶׁיִּהְיֶה בִּימֵיהֶם לְפָרַשׁ לָהֶם דְּבָרִים קָשִׁים שֶׁבַּתַּלְמוּד, וְהֶם מְשִׁיבִים לָהֶם כְּפִי חָכְמָתָם; וְאוֹתָן הַשּׁוֹאֲלִין מְקַבְּצִין הַתְּשׁוּבוֹת, וְעוֹשִׂין מֵהֶן סְפָרִים לְהָבִין מֵהֶם.

However, in other places, and even in Babylonia in the era of the Geonim, a person cannot understand this language unless he has studied it. the Rambam explains that he chose to compose the Mishneh Torah in Mishnaic Hebrew rather than in Aramaic in order to make it more accessible to the common man. The inhabitants of each city would ask many questions of each Gaon who lived in their age, to explain the difficult matters that existed in the Talmud. They would reply to them according to their wisdom. The people who had asked the questions would collect the replies and make texts from them, so that they could consider them in depth. which began to accumulate from the many questions circulated among the different Jewish communities in the diaspora.