Samuel went to Bethlehem, as the Lord directed, to anoint a king for Israel (cf. 1 Samuel 16:1-13). God chose the youngest and most unlikely of Jesse’s eight sons as His representative because He saw the qualities of David’s heart (while Saul feared the people, David feared God). Thus, He took David from shepherding his father’s sheep to representing Him as prince over Israel (2 Samuel 7:8).
God made an oath to end the tumultuous times Israel experienced during the period of Israel’s Judges (due to their sin and disobedience) and to establish David’s dynasty forever (cf. 2 Samuel 7:4-17). The words of Psalm 89 echo that oath. For the people to sing this faithfully was to acknowledge and accept that this covenant with David (2 Sam. 7:8–16) defined his heir as the divinely appointed representative for God’s people, whose task was to lead them in faithfulness.
God promised that His unfailing love and faithfulness would not depart from David nor his heir to the throne as it had departed from Saul. The king’s power (horn) would be established (exalted) in God’s name (v.24). To exalt his horn was to make a public assertion of power (cf. Psalms 75:4). The king’s hand and right hand (v. 25) was none other than the power and might of the hand of God (cf. v.13) because the king served the people as God’s representative.
Just as Israel is God’s firstborn son (Exodus 4:22), so too the king is the firstborn because he is the embodiment of the people (cf. 2 Samuel 7:14). Jesus is the New Testament firstborn and exalted heir to David’s throne (Romans 8:29; Colossians 1:15, 18; Hebrews 1:6; Revelation 1:5). Jesus fulfills the prospect of being the highest of the kings of the earth (Rev. 1:5; 19:16; cf. Matt. 28:18–19). He is bringing all people to acknowledge God’s faithfulness. In Christ, God’s promise of unfailing love, faithfulness and power finds ultimate fulfillment. Jesus was sent by God to faithfully usher in His Kingdom. Through Him the tumultuous reign of sin (whose power is established in the law) was overturned. His throne is establish as His power and influence reigns in men’s hearts by the grace He extends through faith in His atonement. To faithfully sing His praise is to acknowledge Him as God’s powerfully exalted representative and faithful heir to the throne of His eternal kingdom. Who’s praises do you sing?