We can identify three purposes for this brief section. [source][source][source]
1.Moses explained and justified the reason for Jacob"s later departure for Paddan-aram ( Genesis 27:46 to Genesis 28:2).2.Moses identified the ancestors of the Edomites who later played a major role in Israel"s history.3.Moses revealed Esau"s carnal character again. [source][source][source]
Esau showed no interest in the special calling of his family but sought to establish himself as a great man in the world by marrying Canaanite women (cf. Genesis 11:4). These were evidently the daughters of Canaanite lords. [1] The Canaanites were, of course, under God"s curse ( Genesis 9:25-27). Contrast Esau"s method of securing wives with Abraham"s plan to identify God"s choice of a wife for Isaac. [source][source][source]
"These preliminary notices [2] put into perspective the cunning deed of Jacob and Rebekah. They demonstrate that Esau was not fit to inherit the blessing." [3][source]