John Calvin Commentary Genesis 27:4

"And make me savory food, such as I love, and bring it to me, that I may eat. That my soul may bless thee before I die." — Genesis 27:4 (ASV)

That my soul may bless you. The faith of the holy man was wonderfully blended with a foolish and inconsiderate carnal affection. The general principle of faith flourishes in his mind when, in blessing his son, he entrusts to him, under the direction of the Holy Spirit, the right of the inheritance which had been divinely promised to him.

Meanwhile, he is blindly carried away by the love of his firstborn son, preferring him to the other; and in this way, he contends against the oracle of God. For he could not have been ignorant of what God had pronounced before the children were born. If anyone would excuse him, arguing that he had received no command from God to change the customary order of nature by preferring the younger to the elder, this excuse is easily refuted. For when he knew that the firstborn was rejected, he still persisted in his excessive attachment.

Again, in neglecting to inquire about his duty when he had been informed of the heavenly oracle by his wife, his laziness was by no means excusable. For he was not entirely ignorant of his calling; therefore, his obstinate attachment to his son was a kind of blindness, which proved a greater obstacle to him than the external dimness of his eyes.

Yet this fault, although deserving of rebuke, did not deprive the holy man of the right to pronounce a blessing; rather, plenary authority remained with him, and the force and effectiveness of his testimony remained intact, just as if God Himself had spoken from heaven—a subject to which I will return shortly.