Sunan Abu Dawud
473
Sahih+3

Abu Hurairah reported:I heard the Messenger of Allah (May peace be upon him) 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

SahihAl-Albani
SahihMuhammad Muhyi Al-Din Abdul Hamid