מדרש אויף דברי הימים א 5:20

It was taught in the name of R. Pepiyas: Indeed it is a disgrace for Hezekiah and his associates not to have recited any song until the earth opened its mouth and sang, as it is said, (Is. 24) From the edge of the earth we heard songs, Glory be to the righteous. Similar to this we find a passage (Ex. 18, 10) Blessed be the Lord who hath delivered you. It was taught in the name of Pepiyas: It is indeed a shame for Moses and the six hundred thousand Israelites with him who didn't say this benediction till Jethro came and said Blessed be the Lord (Ib. ib. 9) Vayichad (rejoiced) Jethro. Rab and Samuel both explain this word. Rab said: "It means that he passed a sharp razor upon his body." [He performed the ceremony of circumcision]. And Samuel said "It means that his whole body pained as if struck with sharp needles." Rab said: "This is what people say: "A proselyte, even until the tenth generation, do not despise in his presence a heathen." (Is. 10, 15) Therefore will the Lord, the Eternal of hosts, send forth among his bmashmanov (fat ones) leanness. What is meant by the term bmashmanov? The Lord said: "Let Hezekiah who has eight names come and take revenge on Sennacherib who has also eight names." Hezekiah had eight names, as it is written (Ib. 9, 5) For a child is born unto us, a son hath been given unto us, and the government is placed on his shoulders and his name is Pete, Yoez, El, Gibor, Abbi, Ad, Sar, Shalom. And what about the name Hezekiah? This means that the Lord strengthened him; according to others, it means, that he caused the strengthening of Israel unto their Heavenly Father. And concerning Sennacherib, it is written (II Kings, 15, 9) Thiglath-pilesser (I Chron. 5, 20) Pilnesser, (II Kings, 17, 3) Shalmanesser, (Ib. ib. 17) Pul, (Isa. 20, 1) Sargon, and (Ezra 4, 70) Assnaper, Rabha, V'yaquira. And what about the name Sennacherib? This means that he said vile words against Heaven. R. Jochanan said: "Why did that wicked one deserve to be called the honored and the great? Because he did not speak evil of the land of Israel, as it is said (II Kings, 18, 32) Until I come and take you away to a land like your own, etc." Rab and Samuel differ in the following: One says he was a clever king, and the other, he was a foolish king. According to the one, he was a clever king, because if he would have said that he would take them to a better land than theirs they would have considered him a liar. And according to the other he was a fool, for what use could it be for them to go to a land which was not better than their own? Whereto did he exile the ten tribes of Israel? Mar Zutra said, to Africa, and R. Chanina said, to the mountains of Slug. However, the ten tribes of Israel slandered the land of Israel, for when they reached the city of Sus they said that it was like their own land. And when they came to the city of Elmin they said that it is like our Elmin (Jerusalem), and when they reached the second Sus they said that it was much better than their own land.

“Gad, a troop will slash his enemies, and he will slash their heel” (Genesis 49:19).
“Gad, a troop will slash his enemies” – when Israel was conquering and distributing the land, the tribes of Reuben and Gad were with them, and they had left their children when they were young.⁹¹These tribes asked for portions of land on the eastern side of the Jordan. Moses agreed, on the condition that they would cross the Jordan and aid the rest of the tribes in conquering the land from the Canaanite nations (see Numbers 32:20–27). The men of these tribes settled their families on the eastern side of the Jordan, aided the rest of the tribes during the fourteen years of conquest and distribution of the land, and only then returned to their families, at the behest of Joshua (see Joshua 22:1–9). One whom they left at the age of ten, they found him twenty-four years old. One whom they left at the age of twenty they found him thirty-four years old. Three wicked families confronted them: Yetur, Nafish, and Kedma; that is what is written: “In the days of Saul, they waged war with the Hagrites, [who fell into their hand, and they dwelled in their tents across all the east of the Gilad]” (I Chronicles 5:10).⁹²The families of Yetur, Nafish, and Kedma descended from Ishmael (see Genesis 25:13–15). They are called Hagrites after Hagar, Ishmael’s mother. Rabbi Yehoshua bar Neḥemya said: “In the days of Saul” – this is Joshua. Why does it call him Saul [Sha’ul]? Because the kingship was borrowed [she’ula] in his hand.⁹³Joshua, the Judges, and King Saul were caretakers of the kingdom until the true king, a descendant of the tribe of Judah, would assume the throne. These would grow their hair, and those would grow their hair; these would grow their hair until they would see their children, and these would grow their hair until they would see their fathers.⁹⁴The men and children of Reuben and Gad would grow their hair as a sign of anguish until they could be reunited. And the Ishmaelites would grow their hair.⁹⁵Consequently, when they returned, the fathers had difficulty distinguishing between their children and the Ishmaelites. The Holy One blessed be He placed into the heart of the children, and they would say: ‘Answer us, Lord, answer us, God of Abraham, God of Isaac, and God of Israel, answer us.’ That is what is written: “They were aided against them, and the Hagrites…were delivered into their hand, [for they cried out to God in the battle, and He acceded to their entreaty]” (I Chronicles 5:20).
Due to what merit? Rabbi Levi and the Rabbis: The Rabbis said: Due to the blessing of Jacob, who said: “Gad, a troop will slash his enemies,” a troop will come to slash them and they will slash the troop. Rabbi Levi said: Due to the blessing of Joshua. That is what is written: “He said to them, stating: [Return to your tents] with much wealth…[divide the spoils of your enemies with your brethren]” (Joshua 22:8).