What is "Tevahel"?
Rashi: It is to hurry. Ibn Ezra - this is like "va'Yavhilu Lehavi Es Haman" (Esther 6:14).
Metzudas David: It is to be easily [angered].
What is "Lich'os"?
Rav Sadya Gaon: It is to be sad and angry.
Why does it say "Al Tevahel b'Ruchacha Lich'os"?
Ibn Ezra (10): A Chacham should not be angry because a Kesil has more money than he does.
Rashbam: Force your Yetzer not to get angry.
R. Avigdor citing Koheles Zuta: This refers to Moshe. Hashem told him, you were angry - "va'Yichar Af Moshe", you threw [the Luchos] - "va'Yashlech mi'Yadav", you broke - "va'Yshaber Osam", so you should make the replacement 1 - "Pesal Lecha" (Shemos 32:19, 34:1).
Metzudas David: When you get angry, do not rush to show your anger.
This seems unlike Shabbos 87a, which expounds "Asher Shibarta" (Shemos 34:1) - you should be strengthened, for you broke them (it was good to do so)! (PF)
What do we learn from "Ki Cha'as b'Cheik Kesilim Yanu'ach"?
Torah Temimah citing Nedarim 22b: Anger makes one forget his learning and increase foolishness. We learn also from "u'Chsil Yifros Iveles" (Mishlei 13:16). Orchos Tzadikim (Sha'ar ha' Ka'as DH ha'Ka'as) - it leads to mistakes. No one is greater than Moshe, and in three places he got angry and erred!
Rashbam: This is why you should force your Yetzer not to get angry - you do not want to be a Kesil, who is irritable.
Seforno: Anger is prepared in their laps and revealed to all, for nothing stops their Ru'ach. They are drawn after their nature, without intending for nice ends.
Metzudas David: Showing anger found a guarded resting place in the lap of Kesilim. It does not abandon them, for they do not consider that their colleagues will shame them. Therefore, a wise person will be quiet at that time, and not get angry quickly.
