Adam Clarke's Bible Commentary Verse 9. Thou shalt break them with a rod of iron ] This may refer to the Jewish nation, whose final rejection of the Gospel was foreseen, and in whose place the Gentiles or heathen were brought into the Church of Christ. They were dispossessed of their land, their city was razed to its foundations, their temple was burnt with fire, and upwards of a million of themselves were slaughtered by the Romans! So heavily did the iron rod of God's judgments fall upon them for their obstinate unbelief.
Matthew Henry Commentary
Verses 7-9 - The kingdom of the Messiah is founded upon an eternal decree of God the Father. This our Lord Jesus often referred to, as what he governe himself by. God hath said unto him, Thou art my Son, and it become each of us to say to him, Thou art my Lord, my Sovereign'. The Son, i asking the heathen for his inheritance, desires their happiness in him so that he pleads for them, ever lives to do so, and is able to save to the uttermost, and he shall have multitudes of willing, loyal subjects among them. Christians are the possession of the Lord Jesus; they ar to him for a name and a praise. God the Father gives them to him, when by his Spirit and grace, he works upon them to submit to the Lor Jesus.
Original Hebrew תרעם7489 בשׁבט7626 ברזל1270 ככלי3627 יוצר3335 תנפצם׃5310