C.H. Spurgeons's The Treasury of David
Verse 24. But my faithfulness and my mercy shall be with him. These were the two attributes of which the Psalmist began to sing in Psalms 89:1, doubtless because he saw them to be most prominent in the covenant which he was about to plead with God. To David and his seed, God was gracious and faithful, and though through their sin the literal kingdom lost all its glory and the dynasty became obscure, yet the line remained unbroken and more than all its former glory was restored by the enthronisation of Him who is Prince of the kings of the earth, with whom the Lord's mercy and faithfulness remain for ever. All who are in Jesus should rejoice, for they shall prove in their own experience the faithful mercy of the Lord.
And in my name shall his horn be exalted. Gloriously does the Lord Jesus lift up his head, raised to the highest place of honour by the mandate of the Father. David and Solomon in their dignity were but faint types of the Lord Jesus, who is far above all principalities and powers. The fullest exaltation of the horn of Jesus is yet to come in that millennial period which is hastening on.