Why do some translations give opposite meanings to Esau’s blessing in Genesis 27:39?

Answer:

The difficulty comes from the Hebrew preposition min. This preposition denotes distance or separation, but it doesn't indicate by itself the direction of the separation. Thus, if I give you something, it is separated from me. If something is taken from you, it is separated from you. In both cases, min is used.

Looking at the literal reading of the verse:

wayya'an (and he answered) yitschaq (Isaac) 'aviw (his father) wayyo'mer (and he said) 'elav (to him) hinneh (behold) mishmanne (from the fat of) ha'arets (the land) yihyeh (it will be) moshavekha (your dwelling) umittal (and from the dew of) hashshamayim (the heavens) me'ai (above)

Albert Barnes notes: "Away from the fatness. The preposition (מן min) is the same as in the blessing of Jacob. But there, after a verb of giving, it had a partitive sense; here, after a noun of place, it denotes distance or separation; for example, Proverbs 20:3."

So to compare it to Genesis 27:28,

weyitten-iekha (and He will give to you) haeloim (God) mittal (from the dew of) hashshamayim (the heavens) umishmanne (and from the fat of) ha'arets (the land) werov (and abundance of) daghan (grain) wethirosh (and wine)

Notice that almost the same words are used, but the presence of the verb "will give" drastically changes how we view "from." In Genesis 27:28 God gives from, but in Genesis 27:39 Esau is told he will be from.

Comparing different translations of Genesis 27:39 we find:

(NKJV) Then Isaac his father answered and said to him: "Behold, your dwelling shall be of the fatness of the earth, And of the dew of heaven from above.
(NAS95) Then Isaac his father answered and said to him, "Behold, away from the fertility of the earth shall be your dwelling, And away from the dew of heaven from above.
(NIV) His father Isaac answered him, "Your dwelling will be away from the earth's richness, away from the dew of heaven above.
(KJV) And Isaac his father answered and said unto him, Behold, thy dwelling shall be the fatness of the earth, and of the dew of heaven from above;
(ASV) And Isaac his father answered and said unto him, Behold, of the fatness of the earth shall be thy dwelling, And of the dew of heaven from above.
(BBE) Then Isaac his father made answer and said to him, Far from the fertile places of the earth, and far from the dew of heaven on high will your living-place be:
(DBY) And Isaac his father answered and said to him, Behold, thy dwelling shall be of the fatness of the earth, And of the dew of heaven from above;
(MKJV) And Isaac his father answered and said to him, Behold! Your dwelling shall be of the fatness of the earth and of the dew of heaven from above.
(RSV) Then Isaac his father answered him: "Behold, away from the fatness of the earth shall your dwelling be, and away from the dew of heaven on high.
(WEB) Isaac his father answered him, "Behold, of the fatness of the earth will be your dwelling, and of the dew of the sky from above.
(YLT) And Isaac his father answereth and saith unto him, `Lo, of the fatness of the earth is thy dwelling, and of the dew of the heavens from above;
(NASB) Then Isaac his father answered and said to him, "Behold, away from the fertility of the earth shall be your dwelling, And away from the dew of heaven from above.
(NRSV) Then his father Isaac answered him: "See, away from the fatness of the earth shall your home be, and away from the dew of heaven on high.

The problem that arises is that "of" is also a proper translation of min when used in the sense of "a portion of." All the translations used "of" to translate min in Genesis 27:28. I assume some continued to use "of" in Genesis 27:39 to be consistent, but it resulted in a loss of meaning in English. What I find interesting is that "from" could have been used in both verses and the difference in meaning would have been retained in English. But not being a translator, I can't tell you why this wasn't done. But it appears to me that "from" is the more accurate translation of min in Genesis 27:39 and it makes far more sense in the context of what is being said.

It is interesting that in Proverbs 20:3, as Albert Barnes noted, all the translations use "from" or something similar for min.