Sahih Muslim Book 4, Hadith Number 1185.

Chapter : It is forbidden to cry out for finding out the lost thing in the mosque.

Abu Huraira reported: The Messenger of Allah (may peace be upon him) said two rak’ahs of the noon prayer and then gave salutation when a man from Band Sulaim came to him and said: Messenger of Allah, has the prayer been shortened, or have you forgotten? – and the rest of the Hadith is the same.