ONE OF THE FEATURES OF THE PSALMS that describe the enthronement of a Davidic king, or the reign of a Davidic king, is how often the language goes "over the top."
This feature combines with the built-in Davidic typology to give these psalms a twin focus. On the one hand, they can be read as somewhat extravagant descriptions of one of the Davidic kings (in this case Solomon, according to the superscription); on the other, they invite the reader to anticipate something more than a David or a Solomon or a Josiah.
So it is in Psalm 72. On the one hand, the Davidic monarch was to rule in justice, and it is entirely appropriate that so much of the psalm is devoted to this theme. In particular, he is to take the part of the afflicted, "the children of the needy" (Ps. 72:4), those "who have no one to help" (72:12). He is to oppose the oppressor and the victimizer, establishing justice and stability, and rescuing those who would otherwise suffer oppression and violence (72:14).
His reign is to be characterized by prosperity, which is itself "the fruit of righteousness" (72:3 — a point the West is rapidly forgetting). Gold will flow into the country, the people will pray for their monarch; grain will abound throughout the land (72:15-16).
On the other hand, some of the language is wonderfully extravagant. Some of this is in line with the way other ancient Near Eastern kings were extolled. Nevertheless, combined with the Davidic typology and the rising messianic expectation, it is difficult not to overhear something more specific. "He will endure as long as the sun, as long as the moon, through all generations" (72:5) — which may be true of the dynasty, or may be an extravagant wish for some purely human Davidic king, but is literally true of only one Davidic king. "He will rule from sea to sea and from the River (i.e., the Euphrates) to the ends of the earth" (72:8) — which contains a lovely ambiguity. Are the "seas" no more than the Mediterranean and Galilee? Should the Hebrew be translated (as it might be) more conservatively to read "the end of the land"?
But surely not. For not only will "the desert tribes" (i.e., from adjacent lands) bow before him, but the kings of Tarshish — Spain! — and of other distant lands will bring tribute to him (72:9-10). Moreover: "All kings will bow down to him and all nations will serve him" (72:11). "All nations will be blessed through him, and they will call him blessed" (72:17) — as clear an echo of the Abrahamic covenant as one can imagine (Gen. 12:2-3).
One greater than Solomon has come (Matt. 12:42).
Numbers 28; Psalm 72; Isaiah 19-20; 2 Peter 1