Rashi: The day when he gets angry, he informs his anger. He confronts and reviles his colleague in public. Nothing stops his Ru'ach.

R. Yonah: On the day that they anger him with quarrels, he makes the amount of his anger known. He will tell to the masses what crosses his mind regarding vengeance from his colleague. He tells his entire heart, all that he plans to do. This is foolish for two reasons. (a) He informs all how others disgraced him, and reveals his disgrace to those who did not know it. (b) He exposes his secret; his colleague will know to be careful from him and guard from his plot - "Hafer Machashavos b'Ein Sod" (15:22).

Malbim: It is the way of Chachmah, Tevunah and Sechel to delay anger and not show it immediately. Anger itself is a lowly Midah. It is a disgrace for him; it is good to cover it. It testifies about his evil nature - "Sechel Adam He'erich Apo", "Erech Apayim Rav Tevunah" (19:11, 14:29). An Evvil did not plant the laws of Chachmah in his Nefesh to conduct according to them - "Ketzar Apayim Ya'aseh Iveles" (14:17). Immediately on the day of his anger he reveals it to all and brings it out in practice. A law of Chachmah and Tevunah is to delay anger and not take vengeance. Vengeance, bearing a grudge and doing evil to his colleague, even though his colleague sinned against him, oppose the laws of Chachmah. Even one who did not learn the laws of Chachmah would do so amidst prudence. If he gets angry, his colleague will disgrace him, and he will be disgraced in front of those who see and hear.

Rashi: The Arum covers disgrace. He does not rush to quarrel.

Rashi citing a Midrash: On the day that Adam ha'Rishon was created, his sin became known; Hashem, who is Arum, did not want to destroy His creations. He covered Adam's shame, and pushed off His decree ("b'Yom Achalcha Mimenu Mos Tamus" - Bereishis 2:17) from one of Adam's days to one of His days, which is 1000 years.

R. Yonah: It goes without saying that he does not reveal his anger and hides the secrets of his heart. Rather, even the insults that were said to him, he covers.

Malbim: An Arum covers disgrace, so he will not get disgrace. Therefore, he covers his anger in his heart, until he has opportunity to take vengeance in a way that will not cause disgrace to himself. This is from Armah, and not from Chachmah; Chachmah commands to cover anger itself, and it should not rule over even his hidden Ru'ach ¹ .