Verse 4. Thy seed will I establish for ever. David must always have a seed, and truly in Jesus this is fulfilled beyond his hopes. What a seed David has in the multitude which have sprung from him who was both his Son and his Lord. The Son of David is the Great Progenitor, the second Adam, the Everlasting Father, he sees his seed, and in them beholds of the travail of his soul.
And build up thy throne to all generations. David's dynasty never decays, but on the contrary, is evermore consolidated by the great Architect of heaven and earth. Jesus is a king as well as a progenitor and his throne is ever being built up -- his kingdom comes -- his power extends.
Thus runs the covenant; and when the church declines, it is ours to plead it before the ever faithful God, as the Psalmist does in the latter verses of this sacred song. Christ must reign, but why is his name blasphemed and his gospel so despised? The more gracious Christians are, the more will they be moved to jealousy by the sad estate of the Redeemer's cause, and the more will they argue the case with the great Covenant maker, crying day and night before him, "Thy kingdom come."
Selah. It would not be meet to hurry on. Rest, O reader, at the bidding of this Selah, and let each syllable of the covenant ring in thine cars; and then lift up the heart and proceed with the sacred poet to tell forth the praises of the Lord.