Abu Hurairah (RA) reported: The Messenger of Allah (ﷺ) said: If anyone bears a man crying out in the mosque about something lie has lost, he should say: May Allah not restore it to you, for the mosques were not built for this.
Hadith Referenceصحيح مسلم / كتاب المساجد ومواضع الصلاة / 568
Abu Hurairah reported: I heard the Messenger of Allah ﷺ as saying; if anyone hears a man crying out in the mosque about something he has lost, he should say: May Allah not restore it to you, for the mosque were not built for this.
Shaykh Umar Farooq Saeedi
473. Commentary: It is permissible to make an announcement near the door outside the mosque. «ضالة» refers to a lost animal, while a lost object is called «ضائع». The same ruling applies to it. There is a difference of opinion among the scholars regarding making announcements in mosques about lost children. Some permit it, while others do not. However, in view of human dignity and compassion, there is room for permissibility in this matter, even though most scholars do not allow it.
Source: Sunan Abu Dawood – Commentary by Shaykh Umar Farooq Saeedi, Page: 473