מדרש אויף תהילים 105:38

Another interpretation: “This month shall be for you” – that is what is written: “[He brought out His people with joy and his chosen ones with gladness.] He gave them lands…so that they would observe His statutes” (Psalms 105:43–45). God brought the plagues upon the Egyptians: “He sent darkness, and it was dark” (Psalms 105:28); He gradually lowered [the darkness] until it reached Egypt. “Egypt rejoiced at their departure” (Psalms 105:38) – it is analogous to a king whom everyone honored. To what degree did they honor him? To the extent that they would bring him gifts and would present their gods with them. So, Pharaoh ruled from one end of the world to the other end, and they would bring him gifts and present their gods with them. Then Moses and Aaron came, as it is stated: “Then Moses and Aaron came…” (Exodus 5:1). He took out his lists²⁹Lists of the names of all the gods. and searched them but did not find this [God’s] name.³⁰See Exodus 5:2: “Pharaoh said: Who is the Lord, that I should heed His voice to send forth Israel? I do not know the Lord, and I also will not send forth Israel.” This is analogous to a servant who was walking with his master…as cited above.³¹Shemot Rabba 5:14
But the Holy One blessed be He is living and everlasting, as it is stated: “But the Lord God is the true God, He is the living God, and the eternal King” (Jeremiah 10:10). It is analogous to a poor person who was in the city and stood before the king [to ask for assistance], but he was indifferent [to the poor person’s suffering]. When the affliction affected his own body he said: There is nothing like this. So, the Holy One blessed be He brought plagues upon the Egyptians, but Pharaoh was indifferent. When it afflicted his body, he was affected and began screaming: “The Lord is righteous, and I and my people are wicked” (Exodus 9:27).
Could the Holy One blessed be He not have rescued Israel from the hand of Egypt with the first plague? Rather, it was to fulfill what is stated: “He exalts the nations and eliminates them” (Job 12:23), and it is written: “He removes the heart of the leaders of the people of the land” (Job 12:24). Why did he say: “The Lord is righteous?” When the plagues came, they came only in the land of Egypt. Even if a plague was introduced there and entered like [the size of] an almond, the plague would fill all of it but would not touch another field [outside of Egypt]. About this it is stated: “For when Your judgments are on the earth, [the inhabitants of the world] learn righteousness” (Isaiah 26:9). To what was the congregation of Israel comparable? To a king who had a beloved daughter, who was located across the river; the king extended his hand and brought her over and seated her in his chariot, as it is stated: “How beautiful are your steps” (Song of Songs 7:2); “I did not know myself; he placed me on the chariots of my noble people” (Song of Songs 6:12); “He rained meat upon them like dust” (Psalms 78:27); “He led them through the depths” (Psalms 106:9); “the Lord was going before them by day” (Exodus 13:21).³²All these verses express ways that God expresses his care for Israel. All this was due to the merit of Abraham, as it is stated: “For He remembered His holy word unto Abraham His servant; He took out His people with gladness…and He gave them the lands of the nations” (Psalms 105:42–44). Why? “So they would observe His statutes and keep His laws” (Psalms 105:45).

"Egypt rejoiced at their departure" (Psalms 105:38) Rabbi Berchiah said: this can be compared to a corpulent man that was riding on a donkey. The donkey hopes, "When will he get down from me?!" and [the man] himself hopes, "When will I get off the donkey?!". When he gets down, the man rejoiced and the donkey rejoices. But I don't know who is happier. Such was it when Israel was in Egypt. The plagues were coming on the Egyptians and the Egyptians were hoping, "When will Israel go out?!" And Israel was hoping, "When will the Holy One Blessed Be He redeem us?" When they were redeemed, both these and these were happy, but we don't know who was happier. From what David said: "Egypt rejoiced at their departure", we know that Egypt was happier.

"When the Israelites left Egypt," as it says in the verse (Psalms 105:38), "Egypt was glad when they departed." Rabbi Berechiah said, "This can be compared to a meat seller riding on a donkey..." When David saw how joyful the Israelites were when they left Egypt, he began to mock the Egyptians for their departure, as it says, "When the Israelites left Egypt." And the verse (Psalms 68:5) says, "Sing to God, sing praises to His name; extol Him who rides on the clouds." What does it mean, "extol Him who rides on the clouds?" It is similar to what is said (Job 7:7), "Do not gaze at me, and I shall not exist." Another explanation of "Sing to God" is that they said before Him songs and hymns. And what does "extol" mean? Rabbi Yehuda says it means "destroy," and Rabbi Nehemiah says it means "clear the way before Him," as it is said (Isaiah 62:10), "Clear the way, clear the way, remove the obstacles from the road of my people." The Sages say there are two heavens, as it says (Psalms 68:34), "Ascribe strength to God; His majesty is over Israel, and His strength is in the skies." The Sages say there are three, as it says (Deuteronomy 10:14), "Behold, the heavens and the heaven of heavens belong to God." Rabbi Eliezer says there are seven: heaven, firmament, clouds, throne, dwelling, place, and the wilderness. And the glory of the Holy One, blessed be He, is in the wilderness, as it is said (Psalms 68:5), "Extol Him who rides on the clouds; His name is the Lord, and exult before Him." What is meant by "wilderness?" Rabbi Tachlifa ben Yaakov said in the name of Rabbi Yehuda bar Simon that the Holy One, blessed be He, saw the deeds of the righteous and was pleased with them. Rabbi Pinchas HaKohen bar Chama said, "The sky, whose name is 'wilderness,' is sown with the deeds of the righteous, and it produces fruit." And in the verse (Psalms 68:5), "His name is the Lord," Rabbi Yehuda HaNasi asked Rabbi Shmuel bar Nachman what is meant by "His name." He said to him, "There is no place where a person is not appointed to oversee his coming, except for the Holy One, blessed be He, who is appointed to oversee His own coming, as it says, 'His name is the Lord.'" Therefore, do not read it as "His name," but as "His coming." Rabbi Yehuda HaNasi lamented that a certain tradition had been lost, as Rabbi Elazar had learned something from his teacher, but had not taught it to him. However, Rabbi Elazar's wife revealed it to him, saying, "Thus did my husband teach me." But Rabbi Yehuda HaNasi did not reveal the teaching, as he had been rebuked by his own teacher for revealing a secret. Rabbi Yehuda HaNasi said, "It is a shame that we lose things and they are not forgotten. A certain maiden once asked Rabbi Elazar his name, but did not tell me hers. Instead, she asked me, 'What is His name, composed of these two letters, by which God created two worlds?' As it is said, 'For in Yah the Lord created the worlds' (Isaiah 26:4), spelled with the letters yod and hei. We do not know if this world was created with the letter yod and the World to Come with the letter hei, or vice versa. However, since it is written, 'These are the generations of the heaven and the earth when they were created' (Genesis 2:4), 'when they were created' refers to God, meaning that this world was created with the letter yod. Why is the letter hei open on the bottom and closed on all sides? So too with this world, everything that is created in it goes down to Sheol (the grave). And that same prick that is in it is a hint to the resurrection of the dead. The World to Come was created with the letter hei. Why is the letter yod tall and bent over? So that the faces of the wicked will be bent in the future. Another interpretation: Why is the letter yod small and bent over? So that the faces of the wicked will be humbled in the future, as it is said, 'And the haughtiness of man shall be brought low' (Isaiah 2:17). When David saw that God created two worlds with these two letters, he began to praise God with hallelujah."