Blessed be the Lord God of Shem. Noah blesses his other children, but in a different manner. For he places Shem in the highest post of honor. And this is the reason why Noah, in blessing him, breaks forth in the praise of God, without adhering to the person of man. For the Hebrews, when they are speaking of any rare and transcendent excellence, raise their thoughts to God. Therefore the holy man, when he perceived that the most abundant grace of God was destined for his son Shem, rises to thanksgiving. Whence we infer, that he spoke, not from carnal reason, but rather treated of the secret favors of God, the result of which was to be deferred to a remote period. Finally, by these words it is declared, that the benediction of Shem would be divine or heavenly.

And he said, blessed be the Lord God of Shem,.... Shem was blessed before Japheth, because he was the first and principal in advising and conducting the affair before ascribed to them, as Jarchi on Genesis 9:23 suggests; and though the words are in the form of an ascription of blessedness to God, the fountain of all good, and by whose grace Shem was influenced and enabled to do the good he did, for which the Lord's name was to be praised and blessed; yet it includes the blessing of Shem, and indeed the greatest blessing he could possibly enjoy; for what greater blessing is there, than for a man to have God to be his God? this includes everything, all blessings temporal and spiritual; see Psalm 144:15 some interpret the God of Shem of Christ, who, according to the human nature, was a descendant of Shem; and according to the divine nature the God of Shem, God over all, blessed for ever, Romans 9:4.
And Canaan shall be his servant; the posterity of Canaan be servants to the posterity of Shem: this was fulfilled in the times of Joshua, when the Israelites, who sprung from Shem, conquered the land of Canaan, slew thirty of their kings, and took their cities and possessed them, and made the Gibeonites, one of the states of Canaan, hewers of wood and drawers of water to them, or the most mean and abject servants.

Blessed be the Lord God of Shem--rather, "Blessed of Jehovah, my God, be Shem,"--an intimation that the descendants of Shem should be peculiarly honored in the service of the true God, His Church being for ages established among them (the Jews), and of them, concerning the flesh, Christ came. They got possession of Canaan, the people of that land being made their "servants" either by conquest, or, like the Gibeonites, by submission [Joshua 9:25].

In contrast with the curse, the blessings upon Shem and Japhet are introduced with a fresh "and he said," whilst Canaan's servitude comes in like a refrain and is mentioned in connection with both his brethren: Blessed be Jehovah, the God of Shem, and let Canaan be servant to them." Instead of wishing good to Shem, Noah praises the God of Shem, just as Moses in Deuteronomy 33:20, instead of blessing Gad, blesses Him "that enlargeth Gad," and points out the nature of the good which he is to receive, by using the name Jehovah. This is done "propter excellentem benedictionem. Non enim loquitur de corporali benedictione, sed de benedictione futura per semen promissum. Eam tantam videt esse ut explicari verbis non possit, ideo se vertit ad gratiarum actionem" (Luther). Because Jehovah is the God of Shem, Shem will be the recipient and heir of all the blessings of salvation, which God as Jehovah bestows upon mankind. למו = להם neither stands for the singular לו (Ges. 103, 2), nor refers to Shem and Japhet. It serves to show that the announcement does not refer to the person relation of Canaan to Shem, but applies to their descendants.

The God of Shem - All blessings are included in this. This was the blessing conferred on Abraham and his seed, the God of heaven was not ashamed to be called their God, Hebrews 11:16. Shem is sufficiently recompensed for his respect to his father by this, that the Lord himself puts this honour upon him to be his God; which is a sufficient recompense for all our services and all our sufferings for his name.