Hebrews 12:16
2 “Lest there be any fornicator: or profane person, as Esau, who for one morsel of meat sold his birthright.”
And wherein was Esau a “fornicator”? He does not say that Esau was a fornicator. “Lest there be any fornicator,” he says, then, “follow after holiness: lest there be any, as Esau, profane”: that is, gluttonous, without self-control, worldly, selling away things spiritual.
“Who for one morsel of meat sold his birthright,” who through his own slothfulness sold this honor which he had from God, and for a little pleasure, lost the greatest honor and glory. This was suitable to them. This [was the conduct] of an abominable, of an unclean person. So that not only is the fornicator unclean, but also the glutton, the slave of his belly. For he also is a slave of a different pleasure. He is forced to be overreaching, he is forced to be rapacious, to behave himself unseemly in ten thousand ways, being the slave of that passion, and oftentimes he blasphemes. So he accounted “his birthright” to be nothing worth. That is, providing for temporary refreshment, he went even to the [sacrifice of his] “birthright.” So henceforth “the birthright” belongs to us, not to the Jews. And at the same time also this is added to their calamity, that the first has become last, and the second, first: the one, for courageous endurance; the other last for indolence.
Source: Homilies on the Epistle to the Hebrews (New Advent)