מדרש אויף תהילים 101:5

R. Chisda said in the name of Mar Ukba: "Every man who possesseth haughtiness, the Holy One, praised be He! says concerning him: 'I and he cannot live in the same world,' as it is said (Ib. 101, 5) Who slandereth in secret his neighbor, him will I destroy; Whoso is proud of eye, and haughty of heart, him could I not bear." Do not read Otho [him], but read Itho [with him.] But others, however, explain the above passage to refer to tale-bearers, as it is said. Whoso slandereth in secret his neighhor. R. Alexanderi said: "Whoever possesses haughtiness, even in the slightest degree, it shall cause his downfall, as it is said (Is. 57, 20) But the wicked are like the troubled sea; jar it can never be at rest. If the sea, which contains so many quarts of water, is nevertheless stirred up by the slightest breeze, how much more so should slight assumption affect a man in whom there is only one quart of blood?" R. Chiya b. Ashi said in the name of Rab: "A scholar should possess one-eighth of an eighth (one-sixty-fourth) of pride." R. Huna, the son of R. Joshua, said: "This befits a scholar like the ears of the standing crop grain." Raba said: "Under ban should be anyone who possesses it on a great scale; under ban, and again under ban, should be the one who does not possess it at all." R. Isaac, however, said: "Neither the whole nor a bit should one possess, for how can we consider so light the warning, (Pr. 16, 5) An abomination of the Lord is everyone that is proud of heart."

“The Lord said to him further: Put your hand in your bosom. He put his hand in his bosom and took it out, and behold, his hand was leprous, like snow” (Exodus 4:6).
“The Lord said to him further: Put your hand in your bosom.” He said to him: ‘It is just like the serpent who, when he engaged in slander, I afflicted him with leprosy, as it is stated: “Cursed [arur] are you from all the animals” (Genesis 3:14), as you say: “Malignant [mameret] leprosy”’ (Leviticus 13:51). Rabbi Elazar said: Those spots on it [the serpent] are leprous marks; so do you deserve to be afflicted with leprosy. Why did he place it in his bosom? It is because slander is typically told in secret. Likewise it says: “He who slanders his neighbor in secret, I will destroy [atzmit]” (Psalms 101:5). Atzmit [refers to] nothing but leprosy, as it is stated: “In perpetuity [litzmitut]” (Leviticus 25:23), which is translated as completely [laḥalutin]²⁹In Targum Onkelos. and it is taught: “The difference between a quarantined leper and a confirmed leper [muḥlat] is only… (Megilla 8b).”³⁰The midrash cites the mishna to show that the word muḥlat, which is derived from the same root as laḥalutin, is used in the context of leprosy.
“He put his hand in his bosom and took it out, and behold, his hand was leprous, like snow.” He received his due because he engaged in slander. Rabbi Yehoshua of Sikhnin said in the name of Rabbi Levi: From here you learn that anyone who suspects another of something which is untrue of him, is afflicted in his body.
“He said: Put your hand back in your bosom. He put his hand back in his bosom; and he removed it from his bosom, and behold, it was restored like his flesh” (Exodus 4:7).
“He said: Put your hand back in your bosom.” How is there a sign for Israel in this? [It is as if God were saying:] Go and say to them: Just as a leper causes impurity, so do the Egyptians render you impure. And just as he [the leper] is purified, so is the Holy One blessed be He destined to purify Israel, as it is written: “And behold, his hand was leprous, like snow,” and in the healing it is written: “He removed it from his bosom, and behold, it was restored like his flesh.” Our Rabbis say: So as not to cast aspersions on Moses’s flesh [i.e. his bosom]; therefore, his hand was not afflicted with leprosy until he removed it from his bosom. However, regarding the healing, it was healed in his bosom. Alternatively, from here punishments are delayed before being exacted upon the righteous, while the [divine] attribute of goodness takes effect quickly.
“And it shall be that if they do not believe even these two signs, and they do not heed your voice, you shall take from the water of the Nile and pour it out on dry land; and the water that you take from the Nile will become blood on the dry land” (Exodus 4:9).
“It will be, if they will not believe even these two…” Why did the Holy One blessed be He perform three signs for him? It is corresponding to Abraham, Isaac, and Jacob.
“You shall take from the water of the Nile.” He indicated to him that, by means of something he will say to Israel, the water is destined to be transformed into blood, and he will be punished through it [the water], as it is written: “Hear now, defiant ones” (Numbers 20:10), and he struck the stone and extracted [water], as it is stated: “Behold, He struck the rock, and water flowed out [vayazuvu]” (Psalms 78:20). Vayazuvu is an expression of nothing other than blood, as it is stated: “If a woman will have a flow [yazuv zov] of her blood” (Leviticus 15:25). That is why he struck the stone twice, as initially it produced blood and finally water. In the first two signs, you find that they were restored to their original state, but the sign of the blood was not restored to its original state because He did not wish to forgive Moses for the sin of the water. And how was there a sign for Israel in this? He said to them: ‘With this sign the Egyptians will be afflicted first.’

“Moses said to the Lord: Please my Lord, I am not a man of words, neither yesterday, nor the day before, nor since You spoke to Your servant; for I am slow of speech, and slow of tongue” (Exodus 4:10).
“Moses said to the Lord: Please my Lord [Adonai].”³¹The name of the Lord is spelled alef, dalet, nun, yod. Moses said to the Holy One blessed be He: ‘You are the lord [adon] of the world, and it is me you want to be an emissary? “I am not a man of words…”’ The Sages said: Seven days previously, the Holy One blessed be He was inducing Moses to go on His mission, but he did not want to go until the incident at the bush. That is what is written: “I am not a man of words,” one; “yesterday,” two; “neither [gam],” three; “the day before,” four; “nor [gam],” five; “since,” six; “You spoke,” seven.
“The Lord said to him: Who makes a man's mouth, or makes a man mute, or deaf, or sighted, or blind? Is it not I, the Lord? Now, go, and I will be with your mouth, and teach you what you shall speak” (Exodus 4:11-12).
Rabbi Pinḥas HaKohen said; Moses said: ‘I am not a man of words, and I do not see [how] words [can be effective] here, because the person to whom I am going [Pharaoh]³²Presumably, Pharaoh is regarded as a slave because Ham is the ancestor of Egypt and the descendants of Ham are cursed with slavery. See Genesis 9:25. Alternatively, “the man” refers to the typical Israelite slave. is a slave and he does not accept admonition, as it is stated: “A slave will not be admonished with words” (Proverbs 29:19). <variant reading:="" if="" i="" am="" not="" going="" to="" afflict="" him,="" i="" will="" not="" go,="" immediately:="" “the="" lord="" said="" [to="" him:="" who="" makes="" a="" man's="" mouth,="" or="" makes="" a="" man="" mute,="" or="" deaf,="" or="" sighted,="" or="" blind?="" is="" it="" not="" i,="" the="" lord?]”="">. If I am going to afflict him I will go immediately.’