“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.