אֵ֧לֶּה בְנֵי־עֵשָׂ֛ו וְאֵ֥לֶּה אַלּוּפֵיהֶ֖ם ה֥וּא אֱדֽוֹם׃ (ס)
Itulah anak-anak Esau, dan itulah para kepala kaum mereka. Esau itulah Edom.
Or HaChaim
הוא אדום, who is identical with Edom, etc. This statement is repeated three times in this paragraph. Seeing that G'd has sworn to destroy Edom the Torah had to tell us that Esau is identical with Edom. The Torah also mentioned the town where Esau lived in verse 8; according to Talmudic practice when a statement is not needed in the context in which it is written it may be applied to another context; in this instance the Torah means the town Esau lived in. In verse 19 the Torah also mentions the sons of Esau once more, identifying them with Edom to tell us that all of Esau's descendants will go up in flames at the time when the prophet's assurance (Ovadiah 18) that "Israel will become a flame and Esau the straw to be consumed" will materialise. The reason they are all included is that the Torah has described them all as Edom. All of this is hinted at in Jerusalem Talmud Nedarim 3,5 which describes that in the future Esau will wrap himself in a Talit and occupy a seat amongst the righteous. G'd, however, will remove him from there. Please read what I have written in this connection on verse 31.