Midrasz do Diwrej ha-jamim II 20:37

"And Yithro heard": Yithro had seven names: Yether, Yithro, Chovav, Reuel, Chever, Putiel, Keni. Yether — he added (yiter) a section in the Torah; Yithro — he was "abundant" (yiter) in good deeds. Chovav — he was beloved (chovev) by the L rd. Reuel — he was a "friend" (rea) to the L rd. Chever — he was a "companion" (chaver) to the L rd. Putiel — he "weaned himself" (niftar) from idolatry. Keni — he was zealous (kinei) for Heaven and he acquired (kanah) Torah. Variantly: "And Yithro heard": In the beginning, he was called "Yether," viz. (Exodus 4:18) "And Moses went and he returned to Yether, his father-in-law," and when he "added" good deeds (to himself), a letter (vav) was added to his name. And thus do you find with Avraham. In the beginning he was called "Avram," and when he "added" good deeds, a letter (heh) was added to his name and he was called "Avraham." And thus do you find with Sarah. In the beginning she was called "Sarai," and when she "added" good deeds, a "great" letter (heh) was added to her name and she was called "Sarah." And thus do you find with Yehoshua, viz. (Numbers 13:16) "And Moses called Hoshea the son of Nun Yehoshua." And there are others whose name was diminished, e.g., Efron. In the beginning he was called "Efron," but when he took the money from Abraham, a letter was dropped from his name, viz. (Genesis 23:16) "and Abraham hearkened to Efron," "and Abraham gave the money to Efron." And thus do you find with Yonadav. In the beginning he was called "Yehonadav," but after "that deed" a letter was dropped from his name and he was called "Yonadav," as it is written (II Chronicles 20:37) "When you befriended Achazyahu, etc." — whence the sages ruled: Let one not befriend an evildoer, even to draw him close to Torah.

(Numb. 20:22:) “Then setting out from Kadesh, the whole congregation [of the Children of Israel came to Mount Hor].” This text is related (to II Chron. 20:37), “Because you have joined with Ahaziah,¹⁰⁸Son of Ahab and a wicked king of Israel (I Kings 22:51-52), with whom Jehoshaphat had allied himself (I Kings 22:44; II Chron. 20:35.) the Lord will destroy your work.” [Similarly,] because they made an alliance with this wicked king to pass through his land, they lost this righteous man (i.e., Aaron).¹⁰⁹Numb. R. 19:16. For that reason the death of Aaron¹¹⁰See Numb. 20:28: … AND AARON DIED THERE ON THE TOP OF THE MOUNTAIN. is made [immediately] adjacent after the parashah about the king of Edom, [as stated] (Numb. 20:21-22), “so Israel turned away from them. Then setting out from Kadesh, the whole congregation [of the Children of Israel came to Mount Hor].”¹¹¹Cf. yYoma 1:1 (38ab). What is the meaning of “the whole congregation?” A complete congregation, a congregation which would be entering the land, since those who had come out from Egypt had died. So these were the ones of whom it is written (in Deut. 4:4), “But you who clung to the Lord your God are all alive today.” (Numb. 20:22:) “Mount (hr) Hor (hr).” What is the meaning of “Mount Hor?” A mountain (hr) on top of a mountain (hr), like a small apple on a large apple. Even though a cloud proceeded before them which lowered the high [places] and raised up the low, the Holy One, blessed be He, left [this] mountain as a sample,¹¹²Gk.: deigma. so that they would know what miracles the Holy One, blessed be He, had done for them; as He had not left a mountain in the desert, lest they become weary climbing and descending. Moreover, although the cloud had made all the desert a plain, He left an elevated spot where the tabernacle would have its resting place. He also left three mountains: Mount Sinai for the Divine Presence, Mount Nebo for the burial of Moses, and Mount Hor for the burial of Aaron.

16 (Numb. 20:22) “Then setting out from Kadesh, the whole congregation [of the Children of Israel came to Mount Hor]”: This text is related (to II Chron. 20:37), “Because you have joined with Ahaziah,⁶⁵Son of Ahab and a wicked king of Israel (I Kings 22:51-52), with whom Jehoshaphat had allied himself (I Kings 22:44; II Chron. 20:35.) the Lord will destroy your work.” [Similarly,] because they made an alliance with this wicked king to pass through his land, they lost this righteous man (i.e., Aaron). For that reason the death of Aaron⁶⁶See Numb. 20:28: … AND AARON DIED THERE ON THE TOP OF THE MOUNTAIN. is made [immediately] adjacent after the parashah about the king of Edom. (Numb. 20:21-22), “So Israel turned away from them. Then setting out from Kadesh, [the whole congregation of the Children of Israel came to Mount Hor]”:⁶⁷Cf. yYoma 1:1 (38ab). What is the meaning of “the whole congregation?” A complete congregation, a congregation which would be entering the land, since those who had come out from Egypt had died. So these were the ones of whom it is written (in Deut. 4:4), “But you who clung to the Lord your God are all alive today.” (Numb. 20:22) “Mount (hr) Hor (hr)”: What is [its] meaning? A mountain (hr) on top of a mountain (hr), like a small apple on a large apple. Even though a cloud proceeded before them which lowered the high [places] and raised up the low, the Holy One, blessed be He, left this mountain as a sample,⁶⁸Gk.: deigma. so that they would know what miracles the Holy One, blessed be He, had done for them; as He had not left a mountain in the desert, lest they become weary climbing and descending. Moreover, although the cloud had made all the desert a plain, He left an elevated spot where the tabernacle would have its resting place. He left three mountains: Mount Sinai for the Divine Presence, Mount Nebo for the burial of Moses, and Mount Hor for the burial of Aaron.

(Numb. 20:22:) THEN SETTING OUT FROM KADESH, <THE WHOLE CONGREGATION OF> THE CHILDREN OF ISRAEL CAME <TO MOUNT HOR>. This text is related (to II Chron. 20:37): BECAUSE YOU HAVE JOINED {TO THE WICKED ONE} [WITH AHAZIAH],¹⁵⁵Son of Ahab and a wicked king of Israel (I Kings 22:51-52), with whom Jehoshaphat had allied himself (I Kings 22:44; II Chron. 20:35.) THE LORD WILL DESTROY YOUR WORK. <Similarly,> because they made an alliance with this wicked king to pass through his land, they lost this righteous man (i.e., Aaron).¹⁵⁶Tanh., Numb. 6:14; Numb. R. 19:16. For that reason the death of Aaron¹⁵⁷See Numb. 20:28: … AND AARON DIED THERE ON THE TOP OF THE MOUNTAIN. is added < immediately> after the parashah on the king of Edom. (Numb. 20:21–22:) SO ISRAEL TURNED AWAY FROM THEM. THEN SETTING OUT FROM KADESH, <THE WHOLE CONGREGATION OF THE CHILDREN OF ISRAEL CAME <TO MOUNT HOR….>¹⁵⁸Cf. yYoma 1:1 (38ab).