Genesis 25:33

33.And Jacob said, Swear to me. Jacob did not act cruelly towards his brother, for he took nothing from him, but only desired a confirmation of that right which had been divinely granted to him; and he does this with a pious intention, that he may hereby the more fully establish the certainty of his own election. Meanwhile the infatuation of Esau is to be observed, who, in the name and presence of God, does not hesitate to set his birthright to sale. Although he had before rushed inconsiderately upon the food under the maddening impulse of hunger; now, at least, when an oath is exacted from him, some sense of religion should have stolen over him to correct his brutal cupidity. But he is so addicted to gluttony that he makes God himself a witness of his ingratitude.