The Messenger of Allah ﷺ prohibited buying and selling in the mosque, announcing aloud about a lost thing, the recitation of a poem in it, and prohibited sitting in a circle (in the mosque) on Friday before the prayer. (Using translation from Abū Dāʾūd 1079)
نَهَى رَسُولُ اللهِ ﷺ عَنِ الشِّرَاءِ وَالْبَيْعِ فِي الْمَسْجِدِ وَأَنْ تُنْشَدَ فِيهِ الْأَشْعَارُ وَأَنْ تُنْشَدَ فِيهِ الضَّالَّةُ وَعَنِ الْحِلَقِ يَوْمَ الْجُمُعَةِ قَبْلَ الصَّلَاةِ