It was narrated from Abu ,Abdullah, the freed slave of Shaddad bin Had…. that he heard Abu Hurairah say: "I heard the Messenger of Allah p.b.u.h say: '"Whoever hears a man making a lost-and-found announcement in the Masjid, let him say: "May Allah not return it to you!" For the Masjids were not built for that.'" (Sahih)