And said, art thou my very son Esau?.... Still having some doubt on his mind whether he really was so or not, because of his voice:
and he said, I am; as for the observation of Jarchi upon this, in order to excuse Jacob from lying, that he does not say, "I am Esau", only "I", it will not do, since it is an answer to Isaac's question, with a design to deceive him; and he intended by it that he should understand him as he did, that he was really Esau.

After his father, in order to get rid of his suspicion about the voice, had asked him once more, "Art thou really my son Esau?" and Jacob had replied, "I am" (אני = yes), he told him to hand him the savoury dish that he might eat. After eating, he kissed his son as a sing of his paternal affection, and in doing so he smelt the odour of his clothes, i.e., the clothes of Esau, which were thoroughly scented with the odour of the fields, and then imparted his blessing (Genesis 27:27-29). The blessing itself is thrown, as the sign of an elevated state of mind, into the poetic style of parallel clauses, and contains the peculiar forms of poetry, such as ראה for הנּה, הוה for היה, etc. The smell of the clothes with the scent of the field suggested to the patriarch's mind the image of his son's future prosperity, so that he saw him in possession of the promised land and the full enjoyment of its valuable blessings, having the smell of the field which Jehovah blessed, i.e., the garden of paradise, and broke out into the wish, "God (Ha-Elohim, the personal God, not Jehovah, the covenant God) give thee from the dew of heaven, and the fat fields of the earth, and plenty of corn and wine," i.e., a land blessed with the dew of heaven and a fruitful soil.
In Eastern countries, where there is so little rain, the dew is the most important prerequisite for the growth of the fruits of the earth, and is often mentioned therefore as a source of blessing (Deuteronomy 33:13, Deuteronomy 33:28; Hosea 14:6; Zac 8:12). In משׁמנּי, notwithstanding the absence of the Dagesh from the שׁ, the מ is the prep. מן, as the parallel מטּל proves; and שׁמנּים both here and in Genesis 27:39 are the fat (fertile) districts of a country. The rest of the blessing had reference to the future pre-eminence of his son. He was to be lord not only over his brethren (i.e., over kindred tribes), but over (foreign) peoples and nations also. The blessing rises here to the idea of universal dominion, which was to be realized in the fact that, according to the attitude assumed by the people towards him as their lord, it would secure to them either a blessing or a curse. If we compare this blessing with the promises which Abraham received, there are two elements of the latter which are very apparent; viz., the possession of the land, in the promise of the rich enjoyment of its produce, and the numerous increase of posterity, in the promised dominion over the nations. The third element, however, the blessing of the nations in and through the seed of Abraham, is so generalized in the expression, which is moulded according to Genesis 12:3, "Cursed be every one that curseth thee, and blessed be he that blesseth thee," that the person blessed is not thereby declared to be the medium of salvation to the nations. Since the intention to give the blessing to Esau the first-born did not spring from proper feelings towards Jehovah and His promises, the blessing itself, as the use of the word Elohim instead of Jehovah or El Shaddai (cf. Genesis 28:3) clearly shows, could not rise to the full height of the divine blessings of salvation, but referred chiefly to the relation in which the two brothers and their descendants would stand to one another, the theme with which Isaac's soul was entirely filled. It was only the painful discovery that, in blessing against his will, he had been compelled to follow the saving counsel of God, which awakened in him the consciousness of his patriarchal vocation, and gave him the spiritual power to impart the "blessing of Abraham" to the son whom he had kept back, but whom Jehovah had chosen, when he was about to send him away to Haran (Genesis 28:3-4).