What does Genesis 27:28 mean?
Isaac is conferring his official blessing, the family blessing, to Jacob (Genesis 27:1–5). He had intended to give this blessing to Esau, of course (Genesis 25:28), but Rebekah and Jacob have successfully deceived Isaac into thinking he is doing just that (Genesis 27:6–10).This raises a question. Is a blessing like this something that can be mistakenly passed on from a father to the wrong son? Are the words of the blessing magic that can be pronounced only once and then are spent? Can the God who will fulfill this blessing be so easily manipulated?
The answer, of course, is no. As has already been demonstrated, the gist of this on Jacob is what God had planned all along. The oracle God gave to Rebekah prior to the birth of her sons stated clearly that the older, Esau, would serve the younger, Jacob (Genesis 25:23). Rebekah had held on to that revelation all along. Isaac, apparently, had not agreed to it. Thus, Rebekah has deceived him into doing what God had said would happen in the first place. This is not a good choice on her part, however—the fallout from this act of fraud will mean never seeing Jacob again (Genesis 27:43–44).
Here Isaac, as the patriarch of the family who holds the covenant with God, prays for Jacob to be blessed with wealth in the form of the dew of heaven, meaning moisture for crops, the fat of the land, and plentiful grain and wine.