He Rejoices Because He Knows That YHWH Will Be The Protector Of All His People (Psalms 28:8-9).
But the Psalmist is not only concerned for himself. His concern is for all God's people. And he rejoices because what God is for him, He also is for them. He has now become one of God's intercessors. This was in fact one of the king's privileges. He could approach God on behalf of his people because he was a priest for ever after the order of Melchizedek (Psalms 110:4). But that is also our privilege too, for we have become sons of the King, called upon to reign with Him (Revelation 5:10; Revelation 20:4; 1 Corinthians 4:8).
‘YHWH is their strength,
And he is a stronghold of salvation to his anointed.'
Note the change to ‘their'. What YHWH has been for him (his strength and shield,) He is also for His people. He is their strength and their stronghold, the strength on which they can constantly draw, the stronghold into which they can enter in order to be saved. He is a strong refuge (Psalms 71:7; Psalms 61:3). The righteous run into it and are safe (Proverbs 18:10).
‘To His anointed.' This may refer to the king as the anointed of YHWH and the representative of his people (Psalms 2:2; Psalms 18:50; Psalms 20:6; 2 Samuel 22:51; 2 Samuel 23:1; etc), or to the people themselves, whom God has set apart for Himself under the shelter of His Name. Our blessing too comes because we are sheltered under the Name of His Anointed, even Jesus in Whom we trust.
Save your people,
And bless your inheritance,
Be their shepherd also,
And bear them up for ever.'
So he finishes by calling on God to save His people and bless His inheritance. They are not only His people but of value to Him as well (compare Exodus 19:5-6). And they are something for which He has a responsibility. Thus he asks Him also to be their shepherd and to uphold His people for ever, bearing them up in His arms (compare Isaiah 40:11).
But David could never have dreamed that one day this very Shepherd would come down from above to be the good Shepherd Who would die for His sheep, so that they might follow Him and be given eternal life and total security (John 10:11; John 10:17-18; John 10:27-28). How much more then should we praise the Name of Him When we consider how much He has done for us.