Musar к Ийова 5:2

Our sages of blessed memory warned us to not get angry even for the sake of a mitzva (see Shab.34a, 105b), not even a teacher with his student or a father with his son. This is not to say he should not chastise them, rather he should surely chastise them, just not out of anger, but rather, with no other purpose than guiding them along the right path. Any anger that he shows to them should be only of the face not anger of the heart. Shlomo said: "Be not quick in your spirit to be angry [for anger rests in the heart of fools]" (Kohelet 7:9) and it is written "For anger slays the fool" (Iyov 5:2), and our sages of blessed memory said: "in three ways a man is recognized: through his cup, through his wallet and through his anger" (Eruvin 65b).

JEALOUSY: Jealousy also is nothing but lack of understanding and foolishness. For the jealous person gains nothing for himself nor does he cause any loss to the person he is jealous of. He only causes loss to himself as the verse we mentioned states "jealousy slays the foolish" (Iyov 5:2).