Verses 6 and 7 are the climax of the psalm, the answer sought in verses 1-5 and expounded in verses 8-12.21
2:7 David's reference to the Lord's decree declaring David God's son goes back to the Davidic Covenant (2 Sam. 7:14). There the Lord described the relationship He would have with David and the kings that would succeed him as that of a father with a son. This communicated to David his legitimate right to rule over Israel. The figure connotes warm affection rather than a formal business relationship. In the ancient world a king's son usually succeeded his father on the throne. In Israel, God wanted the kings to regard Him as their Father. >From the giving of the Davidic Covenant onward the term "son"when used concerning one of the Davidic kings became a messianic title. It was in this sense that Jesus spoke of Himself as the Son of God. That was a claim to being the Messiah.22
The "today"in view then is not the day of David's birth but his coronation, the day he became God's "son"by becoming king. Since this psalm deals with a royal coronation, scholars often refer to it as a coronation psalm. God begot David in this metaphor not by creating him, though He did that too, but by setting him on the throne.
2:8 The Father invited His son, David, to ask for his inheritance. As the great universal King, God promised to give him all the nations of the earth for his inheritance (cf. v. 1). David personally never ruled the whole world, but David's Son who would be completely faithful to His heavenly Father will do so someday (i.e., in the Millennium).
2:9 God will deal with all rebellious peoples severely when He sets up the Messiah on His throne. It was customary for the Egyptian Pharaoh to smash votive pottery jars that represented rebellious cities or nations with his scepter.23Perhaps that practice was the source of the imagery used in this verse. "Rule"(NIV) really means "break"(Heb. ra'a'). The emphasis in this verse is on the putting down of rebels rather than the rule that will follow that subjugation. "Rod"describes a shepherd's staff, a fitting scepter for Him who is the Shepherd of all humankind (cf. 23:4; Gen. 49:10; Rev. 2:27; 12:5; 19:15).
