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.

And Jacob said, Swear to me this day; and he sware unto him: and he (l) sold his birthright unto Jacob.
(l) Thus the wicked prefer their worldly conveniences over God's spiritual graces: but the children of God do the opposite.

And Jacob said, swear unto me this day,.... For the more sure and certain confirmation of the bargain; and by this oath oblige himself to let him peaceably enjoy the birthright, nor seek to revoke it, or dispute it with him, or disturb him in the possession of it:
and he sware unto him; that he would abide by the bargain, and never give him any trouble on that account; and hereby he made it over to Jacob as firm as it could be; God himself being appealed to as a witness of it, whose will it was that Jacob should have the birthright, the blessing, and the promises:
and he sold his birthright unto Jacob; with all the privileges and appurtenances of it, and that for one morsel of meat, as in Hebrews 12:16.