صحيح البخاري

Narrated Sulaiman bin Surd:

While I was sitting in the company of the Prophet, two men abused each other and the face of one of them became red with anger, and his jugular veins swelled (i.e. he became furious). On that the Prophet said, "I know a word, the saying of which will cause him to relax, if he does say it. If he says: 'I seek Refuge with Allah from Satan.' then all is anger will go away." Some body said to him, "The Prophet has said, 'Seek refuge with Allah from Satan."' The angry man said, "Am I mad?"