מדרש אויף קהלת 7:9

Rabba b. R. Huna said: "Whoever gets excited has no regard even for the Shechina, as it is said (Ps. 10, 4) The wicked, in the pride of his countenance (saith): 'He will not require; all his thoughts are, there is no God." R. Jeremiah of Diphti said: "He will even forget his studying and will increase in foolishness, as it is said (Ecc. 7, 9) For anger resteth in the bosom of fools; and again it is written (Pr. 13, 16) But a fool spreadeth abroad his folly." R. Nachman said: "It is known that the iniquities of such a man are more than his meritorious deeds, as it is said (Ib. 29, 22) A man of anger stirreth up strife, and a man of fury aboundeth in transgression."

Another matter, “carve for yourself” – this is what the verse said: “Do not be hasty in your spirit to become angry, as anger abides in the bosom of fools” (Ecclesiastes 7:9). Who was it who became angry? It was Moses, as it is stated: “Moses’ wrath was enflamed and he cast the Tablets from his hands” (Exodus 32:19). The Holy One blessed be He said to him: ‘So, Moses, do you vent your fury on the Tablets of the covenant? Do you seek that I will vent My fury, and you will see that the world will be unable to endure for even one hour?’ He said to Him: ‘What can I do?’ He said to him: ‘I will impose a penalty on you: You shattered them, you replace them.’ That is what is written: “Carve for you two Tablets of stone.”

“Pharaoh's heart was hardened, and he did not heed them, as the Lord had spoken. The Lord said to Moses: Pharaoh's heart is stubborn, he refuses to let the people go. Go to Pharaoh in the morning; behold, he goes out to the water; and you shall stand by the Nile bank to meet him; and the staff that was transformed into a serpent you shall take in your hand (Exodus 7:13–15).
“Pharaoh’s heart was hardened.… The Lord said to Moses: Pharaoh’s heart is stubborn [kaved]” – he is angry. Just as the liver [kaved] becomes angry,¹¹The liver was regarded as the seat of anger; see Berakhot 61b. so, too, this one’s heart became like a liver; he does not understand, he is a fool: “As anger rests in the bosom of fools” (Ecclesiastes 7:9). With what do you chastise the fool? With a staff, as it is stated: “A rod to the back of fools” (Proverbs 26:3). Moses, too, chastised Pharaoh with a staff, as it is stated: “and the staff that was transformed into a serpent [you shall take in your hand].”
Another interpretation: “Pharaoh’s heart is stubborn [kaved]” – the Holy One blessed be He said to him: Wicked one, with the expression with which you honored yourself,¹²Pharaoh honored himself by refusing to humble himself before God. The midrash here is interpreting the word kaved in the sense of kavod, honor. with the same expression I will be honored at your expense, as it is stated: “When I have gained honor [behikavedi] through Pharaoh” (Exodus 14:18).
“Go to Pharaoh in the morning; behold, he goes out to the water” – he would go out to the water only in the morning, because that wicked one would boast and assert that he was a deity and did not need to relieve himself; therefore, he would go out in the morning. Catch him in the morning when he needs to relieve himself. “And the staff that was transformed into a serpent you shall take in your hand” so that he will be afraid of it.