Fatwa ID: 02504
Answered by: Maulana Maruf Ahmed
We are students in a college of education, our leaders in the masjid has stated that no announcement is going to be made in the masjid regarding a lost item even if it is within or inside the masjid. Please what is the ruling on that.
بسم الله الرحمن الرحي
It is disliked to announce lost property in the masjid. 
This is based on a number of ahadith, including the following:
Abu Hurairah narrated that the Prophet said: “Whoever hears a man announcing in the mosque about some objects which he has lost, let him tell him ‘May Allah not return it to you for the mosques are not built for that’.”
You may also read the following fatwa for more information:
Only Allah knows best.
Written by Maulana Maruf Ahmed
Checked and approved by Mufti Mohammed Tosir Miah
Darul Ifta Birmingham
 Ibn Abideen: Radd al-Muhtar, vol. 2, pg. 523, Dar al-Kutub al-Ilmiyyah, Beirut, Lebanon
Saheeh Muslim, Hadith 1288