Matthew Henry Commentary Genesis 28:6-9

"Now Esau saw that Isaac had blessed Jacob and sent him away to Paddan-aram, to take him a wife from thence. And that as he blessed him he gave him a charge, saying, Thou shalt not take a wife of the daughters of Canaan. And that Jacob obeyed his father and his mother, and was gone to Paddan-aram. And Esau saw that the daughters of Canaan pleased not Isaac his father. And Esau went unto Ishmael, and took, besides the wives that he had, Mahalath the daughter of Ishmael Abraham`s son, the sister of Nebaioth, to be his wife." — Genesis 28:6-9 (ASV)

Good examples impress even the ungodly and malicious. But Esau thought, by pleasing his parents in one thing, to atone for other wrongdoings. Carnal hearts tend to think themselves as good as they should be, because in one particular matter they are not as bad as they used to be.