"The structure of Genesis 9:25-27 is a heptastich which is divided into three parts by the repeated refrain of Canaan’s servitude, a son of guilty Ham:
And he said,
Cursed be Canaan;
A servant of servants will he be to his brother.
And he said,
Blessed be the Lord God of Shem;
Let Canaan be a slave to him.
God will enlarge Japhet,
But He will dwell in the tents of Shem;
Let Canaan be a slave to him
Now the key issue is this: Who is the subject of the verb ‘he will dwell’ in Genesis 9:27? We concur with the judgment of the Targum of Onkelos, Philo, Maimonides, Rashi, Aben Ezra, Theodoret, Baumgarten, and Delitzsch that the subject is 'God.' Our reasons are these: (1) the subject of the previous clause is presumed to continue into the next clause where the subject is unexpressed; (2) the use of the indirect object of the previous line as subject (‘Japhet’) would require strong contextual reasons for doing so; (3) the context of the next several chapters designates Shem as the first in honor of blessing; and (4) the Hebrew phrase weyiškōn be’oh°lê šēm, ‘and he will dwell in the tents of Shem,’ hardly makes sense if attributed to Japhet, for Japhet had already been granted the blessing of expansion.
The plan of the whole prophecy appears to devote the first strophe only to Canaan, the second to Shem and Canaan, and the third to all three brothers. On the balance, then, the best option is to regard God as promising to Shem a special blessing. He would dwell with the Semitic peoples. The word for ‘dwell’ is related to the later concept of Mosaic theology of the Shekinah glory of God wherein the presence of God over the tabernacle was evidenced by the pillar of cloud by day and the pillar of fire by night. Hence, the man Shem would be the one through whom the ‘seed’ promised earlier would now come. Had not God said, 'Blessed be the Lord God of Shem’ (Gen. 9:26)? And why did He use this distinctive form of address? Could it not be that the blessing and indwelling were linked? And could it be that they were God’s next provision to earth’s latest crisis?"
-Walter Kaiser, Toward An Old Testament Theology