Sahih Muslim Book 009, Hadith Number 3571.
Chapter: Li'an (Invoking curse).
Abu Huraira (Allah be pleased with him) reported that Sa'd b. Ubada (Allah be pleased with him) said: Messenger of Allah, if I were to find with my wife a man, should I not touch him before bringing four witnesses? Allah's Messenger (may peace be upon him) said: Yes. He said: By no means. By Him Who has sent you with the Truth, I would hasten with my sword to him before that. Allah's Messenger (may peace be upon him) said: Listen to what your chief says. He is jealous of his honour, I am more jealous than he (is) and God is more jealous than I.