Purification (Kitab Al-Taharah)
Dawud :: Book 1 : Hadith 15
Narrated AbuSa'id al-Khudri:
I heard the Apostle of Allah (peace_be_upon_him) say: When two persons go together for relieving themselves uncovering their private parts and talking together, Allah, the Great and Majestic, becomes wrathful at this (action).