Sahih Muslim Book 1, Hadith Number 187.

Chapter : Beating of the cheeks, tearing of the front opening of the shirt, and calling the calls of the Jihillya (Ignorance) are forbidden.

It is narrated on the authority of Abu Burda that Abu Musa fell unconscious and his wife Umm Abdullah came there and wailed loudly. When he felt relief he said: Don’t you know?-and narrated to her: Verily the Messenger of Allah (may peace be upon him) said: I have no concern with one who shaved her hair, lamented loudly and tore (her clothes in grief).