Sahih Bukhari
Virtues and Merits of the Prophet (pbuh) and his Companions
Volume: 004 / Book Number: 056 / Hadith Number: 721
Narrated 'Abdullah (bin Mas'ud):
The Prophet said, "Who-ever slaps his face or tears the bosom of his dress, or calls the calls of the Period of Ignorance, is not from us."