"The Messenger of Allah performed prayer, then a man said: 'Who was looking for the red camel?' The Prophet said: 'May you not find it! The mosques were built for that for which they were built.'"  

صَلَّى رَسُولُ اللَّهِ ﷺ فَقَالَ رَجُلٌ مَنْ دَعَا إِلَى الْجَمَلِ الأَحْمَرِ فَقَالَ النَّبِيُّ ﷺ لاَ وَجَدْتَهُ إِنَّمَا بُنِيَتِ الْمَسَاجِدُ لِمَا بُنِيَتْ لَهُ  

The Messenger of Allah forbade making lost-and-found announcements in the mosque.  

أَنَّ رَسُولَ اللَّهِ ﷺ نَهَى عَنْ إِنْشَادِ الضَّالَّةِ فِي الْمَسْجِدِ  

He heard Abu Hurairah say: "I heard the Messenger of Allah say: 'Whoever hears a man making a lost-and-found announcement in the mosque, let him say: "May Allah not return it to you!" For the mosques were not built for that.'"  

سَمِعْتُ رَسُولَ اللَّهِ ﷺ يَقُولُ مَنْ سَمِعَ رَجُلاً يَنْشُدُ ضَالَّةً فِي الْمَسْجِدِ فَلْيَقُلْ لاَ رَدَّ اللَّهُ عَلَيْكَ فَإِنَّ الْمَسَاجِدَ لَمْ تُبْنَ لِهَذَا