رِيَاضُ الصَّالِحِينَ
Riyad as-Salihin 1696
The Book of the Prohibited actions
Undesirability of Quarrelling or Raising voices in the Mosque
عَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّه عَنْهُ أَنَّهُ سَمِعَ رَسُولَ اللَّهِ صَلَّى اللَّه عَلَيْهِ وَسَلَّمَ يَقُولُ: مَنِ سَمِعَ رَجُلًا يَنْشُدُ ضَالَّةً فِي الْمَسْجِدِ فَلْيَقُلْ: لَا رَدَّهَا اللَّهُ عَلَيْكَ، فَإِنَّ الْمَسَاجِد لم تبنَ لهَذَا ((رَوَاهُ مُسلم)).
Abu Hurairah (May Allah be pleased with him) said: The Messenger of Allah (ﷺ) said, "If anyone hears a man inquiring in the mosque about something he has lost, he should say: 'La raddaha Allahu 'alaika (May Allah not restore it to you),' for mosques are not built for this purpose." [Muslim]
Riyad as-Salihin, 1696