Commento su Genesi 27:28

ויתן לך THEREFORE GOD GIVE THEE — May he give thee and give thee repeatedly (Genesis Rabbah 66:3). However, according to its real meaning it must be connected with the preceding statement — viz., with the words, “See, the smell of my son, which the Holy One, blessed be He, has given him is like the smell of the field etc.“ And may He also give thee of the dew of heaven

OF THE DEW OF HEAVEN. The blessing is not that G-d give him of the dew of heaven for the dew descends in all places. Now had he said that G-d give him an abundance of dew, or that it come in its season, even as it says, Then I will give your rains in their season,²¹⁵Leviticus 26:4. that would have constituted a blessing. Instead, its meaning is as follows: Since above he mentioned G-d’s blessing, As the odor of a field which the Eternal hath blessed,²¹⁶Verse 27 here. meaning “which G-d had blessed for my son”²¹⁷Ramban interprets the phrase, which the Eternal hath blessed, as referring back to the word b’ni (my son), thus making it “the field which G-d had blessed for my son.” Isaac thus continues his blessing by saying, “Just as He has blessed the field for you, my son, may He also give you another blessing, namely, of the dew of the heavens.” — that is, since G-d blessed him in the field by giving him success there in his hunt and by guarding him from death or any mishap — he now says, So G-d give thee, [as an additional blessing], of the dew of heaven, and of the fat places of the earth. It is thus a blessing of addition and abundance. It may be that the expression, And plenty (‘verov’) of corn and wine, is written in the Torah with an extra vav, [which should not affect the meaning], with the sense of the verse being: “So G-d give thee of the dew of heaven and of the places of the earth, i.e., plenty of corn and wine.”
In my opinion the correct interpretation is that G-d’s gift is steady and there is never any interruption in it. Therefore he says, “So G-d give thee for the extent of your days upon your land of the dew of heaven, and give thee of the fat places of the earth,” meaning the fattest of all lands, even as it is written, The beauty of all lands.²¹⁸Ezekiel 20:6.
Now Rabbi Abraham ibn Ezra says that the prefix mem in the word mital, (of the dew) applies to itself and yet to another word, [namely, mishmanei (the fat places of the earth), which is then to be understood as] umimishmanei ha’aretz and from the fat places of the earth.²¹⁹According to Ibn Ezra, reference is thus to the fruits from the fat places of the earth.
To Esau, on the other hand, he gave a blessing which mentions neither through a gift of G-d nor with abundance. Rather he said, “For you too I have reserved a blessing after him: of the fat places of the earth and of the dew of heaven shall your dwelling be.”²²⁰Based on Verse 39 here. That is “as long as you will dwell there,” thereby alluding that he will ultimately be destroyed and lost, for only as long as he will live will his lot be good.

ויתן לך, these words are a continuation of the words אשר ברכו ה' which precede them. They describe the type of blessing G’d will provide for Yaakov (Esau). מטל השמים, essentially what is known as the “blessing of the field.”