Source and decoding - Bava Batra 2a
הַשּׁוּתָּפִין שֶׁרָצוּ לַעֲשׂוֹת מְחִיצָה בְּחָצֵר – בּוֹנִין אֶת הַכּוֹתֶל בְּאֶמְצַע. מָקוֹם שֶׁנָּהֲגוּ לִבְנוֹת גְּוִיל, גָּזִית, כְּפִיסִין, לְבֵינִין – בּוֹנִין; הַכֹּל כְּמִנְהַג הַמְּדִינָה.
Partners who wished to build a partition in a courtyard build the wall in the middle.
Partners who wished to build a partition in a courtyard build the wall in the middle. The building material (rough stone, hewn stone, half-bricks, bricks) follows local practice: everything according to the custom of the land. The Gemara will ask what "partition" means and what "wished" implies.