72:15-17 In return for his beneficent rule the king would receive the blessing of his people. They would express their gratitude by bringing him wealth (cf. 1 Kings 10:10) and by praying for him. As a result of his good influence, his lands would enjoy prosperity that Solomon compared to abundant crops, favored trees, and flourishing citizens. Such a king would enjoy lasting praise, not just the appreciation of the generation he served (cf. Gen. 12:2-3; Rev. 21:24).
72:18-19 Behind the earthly king, Solomon saw the Lord God. If praise came to Solomon, even more credit should go to the God of Israel for enabling the king to exercise such a marvelous reign. Solomon acknowledged God's sovereignty by appealing to Him for the personal equipment he needed to rule justly (vv. 1-11). He also did so by attributing blessing to the Lord here at the end of the psalm.
This closing benediction is a doxology similar to the one that ended Book 1 of the Psalter (Ps. 41:13). Probably the editors of the collection of psalms placed Psalm 72 here because of this doxology and because the whole theme of this psalm is so positive, optimistic, and God honoring.
72:20 This verse was probably an editorial addition rather than a part of Psalm 72 in view of what it says. At least 18 psalms that follow this one were David's (Pss. 86; 101; 103; 108-110; 122; 124; 131; 133; and 138-145). Consequently this verse may have ended an earlier edition of the Psalms rather than the present one. Interestingly the word "prayers"is a synonym for "psalms"as used here. Prayers and praises are the two most characteristic marks of the Psalter.
The theme of Psalm 72 is God's just and righteous rule over the earth. Solomon prayed God might work through him and his administration to bring such a rule to pass. God answered Solomon's petitions largely. However because Solomon proved unfaithful to God his reign was not as great a blessing as it might have been. When Solomon's successor, Jesus Christ, returns to earth and establishes His reign the conditions Solomon requested will find perfect fulfillment. For us Solomon's petitions constitute a model of what the godly should desire and pray for regarding God's just rule on the earth (cf. Matt. 6:10).