Why does the verse teach that he requested the rings?
Malbim: After teaching that he did not desire authority, it teaches that he did not seek spoils. He deserved half the spoils, but he took only a small amount, i.e. the rings, and only as a gift.
What is the meaning of "Ki Yishmaelim Hem"?
Radak: Midyanim are sons of Keturah (Hagar), just like Yishmael. We find that Yishmael bought Yosef, and afterwards they are called Midyanim (Bereishis 37:28). And even if Keturah is not Hagar, both are Bnei Avraham, and they intermarried (Radak there).
Radak, based on Targum Yonasan 1 : The ornaments are from the Aravim who dwell in tents, that they passed through their land when chasing Zevach and Tzalmuna (verse 11).
Malbim: The Midyanim's conduct is like Yishmaelim 2 and Mis'arvim 3 with them, like it says "va'Ya'avru Anashim Midyanim... va'Yimkeru Es Yosef la'Yishmaelim" (Bereishis 37:28).
Targum Yonasan says 'Arava'ei', just like he said on verse 11.
Metzudas David: Both of them wear nose (Ibn Ezra Shemos 32:2 - ear) rings.
'Mis'arvim' connotes mixing with them. Perhaps he cites this verse to show that the Midyanim did business with the Yishmaelim. However, Malbim attributes this to Radak, who says that the names are interchangeable. (PF)
