Allah’s Apostle (peace be upon him) said;
“If any of you becomes ANGRY, let him keep silent.”
(Musnad Ahmad, Book 1 Hadith 329)
Explanation:
This is because in most cases, the angry person loses self control & utter words of kufr or curses, or the word of divorce (talaaq) which would destroy his home, or words of slander which would bring him the enmity & hatred of others.