Sahih Al Bukhari – Book of Good Manners And Form (Al-Adab)

Volumn 008, Book 073, Hadith Number 058.
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Narated By Anas bin Malik RA: The Prophet PBUH was not one who would abuse (others) or say obscene words, or curse (others), and if he wanted to admonish anyone of us, he used to say: "What is wrong with him, his forehead be dusted!"

what a polite way of showing anger. SubhanAllah. Let us try hard to follow this sunnah of being polite when in anger…