Sahih Bukhari
Sahih Bukhari Volume 001, Book 008, Hadith Number 415.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 08. Prayers (Salat)
Narated By Sahl bin Sa'd : A man said, "O Allah's Apostle! If a man finds another man with his wife, (committing adultery) should the husband kill him?" Later on I saw them (the man and his wife) doing Lian in the mosque.