וַתֵּ֣לֶד ל֗וֹ אֶת־זִמְרָן֙ וְאֶת־יָקְשָׁ֔ן וְאֶת־מְדָ֖ן וְאֶת־מִדְיָ֑ן וְאֶת־יִשְׁבָּ֖ק וְאֶת־שֽׁוּחַ׃
Lalu ia melahirkan baginya Zimran, Yoksan, Medan, Midian, Isybak, dan Suah.
Chizkuni
על אודות האשה הכושית, they wondered why Moses had chosen this point in time to separate from Tzipporah and concluded that it was because she was a Negress (ugly), and they could not understand that he had married her in the first place seeing that she had always been a Negress. A different interpretation of this line: She had been a queen in her land, the land of Kush. This would fit with what we have read in Chronicles that Moses had been a King in that land. At the time, he had to marry a local woman. Now there was no need for him to remain married to a Kushite woman. If this were correct, our verse would not refer to Tzipporah, for the line: “for he had married a Kushite woman,” would not make any sense as Tzipporah was a Midianite woman as we know from Exodus 2,21. The Kushites were descended from Cham, the third son of Noach, and as such were a cursed people, and a Jew would not have married a woman from a cursed nation [although, Keturah, Avraham’s second and last wife, was an Egyptian and therefore also from a cursed nation, as Mitzrayim was the second son of Cham, Kush having been his firstborn (Genesis 10,6) Midian himself was a son of Keturah an Egyptian (Genesis 25,2), and therefore descendant of a cursed nation. Ed.]
Rabbeinu Bahya
The Midrash (Sanhedrin 94) views Yitro’s reaction as expressed by the word ויחד somewhat differently, understanding the root of the word as חדד. Accordingly, Yitro had mixed feelings which expressed themselves in goose-flesh at the news of what had overtaken the Egyptians at the Sea of Reeds. The Talmud says that his reaction reflects the truth of the popular saying that a convert displays some sensitivity concerning what befalls his former co-religionists until the tenth generation. Yitro was a tenth generation descendant of Mizrayim the son of Cham, Noach’s youngest son. The Egyptians of his time were his allies. At the same time he himself as a Midianite was also a descendant of Avraham and Keturah (Genesis 25,2) as already mentioned. There had been ten generations between Noach and Avraham. Similarly, there had been ten generations from Cham son of Noach, to Midian son of Avraham. This is the background to the popular saying quoted in the Talmud that the affinity to former associations by a convert is noticeable for ten generations.
Radak
ויעברו אנשים מדינים, these were the Ishmaelites mentioned previously, seeing that both Midianites and Medanites are descendants of Keturah. [Keturah is understood to be Hagar who had her name changed after Sarah’s death when Avraham took her as a wife. Seeing that she gave birth to both Medan and to Midian, (25,2) this made both these sons full brothers to her earlier son Ishmael by the same father. Ed.] Even assuming that Keturah and Hagar were not identical, the three were at least sons of Avraham and therefore half brothers. Their respective families had intermarried so that they could be considered as brothers in the real sense of the word. The close relationship between their respective descendants comes to the fore in Judges 8,24 where after Gideon’s campaign against the Midianites they are described as Ishmaelites, the kind of jewelry they wore identifying them as members of that tribe.