The psalm is not properly a prediction, but a prayer. There is some divergence of opinion as to the proper rendering of the principal verbs,--some, as the A.V. and R.V. (text), taking them as uniformly futures, which is manifestly wrong; some taking them as expressions of wish throughout, which is also questionable; and others recognising pure futures intermingled with petitions, which seems best. The boundaries of the two are difficult to settle, just because the petitions are so confident that they are all but predictions, and the two melt into each other in the singer's mind. The flow of thought is simple. The psalmist's prayers are broadly massed. In vv. 1-4 he prays for the foundation of the king's reign in righteousness, which will bring peace; in vv. 5-7 for its perpetuity, and in vv. 8-11 for its universality; while in vv. 12-15 the ground of both these characteristics is laid in the king's becoming the champion of the oppressed. A final prayer for the increase of his people and the perpetuity and world-wide glory of his name concludes the psalm, to which are appended in vv. 18-20 a doxology, closing the Second Book of the Psalter.
The first petitions of the psalm all ask for one thing for the king--namely, that he should give righteous judgment. They reflect the antique conception of a king as the fountain of justice, himself making and administering law and giving decisions. Thrice in these four verses does "righteousness" occur as the foundation attribute of an ideal king. Caprice, self-interest, and tyrannous injustice were rank in the world's monarchies round the psalmist. Bitter experience and sad observation had taught him that the first condition of national prosperity was a righteous ruler. These petitions are also animated by the conception, which is as true in the modern as in the ancient world, that righteousness has its seat in the bosom of God, and that earthly judgments are righteous when they conform to and are the echo of His. "Righteousness" is the quality of mind, of which the several "judgments" are the expressions. This king sits on an ancestral throne. His people are God's people. Since, then, he is God's viceroy, the desire cannot be vain that in his heart there may be some reflection of God's righteousness, and that his decisions may accord with God's. One cannot but remember Solomon's prayer for "an understanding heart," that he might judge this people; nor forget how darkly his later reign showed against its bright beginning. A righteous king makes a peaceful people, especially in a despotic monarchy. The sure results of such a reign--which are, likewise, the psalmist's chief reason for his petitions--are set forth in the vivid metaphor of ver. 3, in which peace is regarded as the fruit which springs, by reason of the king's righteousness, from mountains and hills. This psalmist has special fondness for that figure of vegetable growth (vv. 7, 16, 17); and it is especially suitable in this connection, as peace is frequently represented in Scripture as the fruit of righteousness, both in single souls and in a nation's history. The mountains come into view here simply as being the most prominent features of the land, and not, as in ver. 16, with any reference to their barrenness, which would make abundant growth on them more wonderful, and indicative of yet greater abundance on the plains.
A special manifestation of judicial righteousness is the vindication of the oppressed and the punishment of the oppressor (ver. 4). The word rendered "judge" in ver. 4 differs from that in ver. 2, and is the same from which the name of the "Judges" in Israel is derived. Like them, this king is not only to pronounce decisions, as the word in ver. 2 means, but is to execute justice by acts of deliverance, which smite in order to rescue. Functions which policy and dignity require to be kept apart in the case of earthly rulers are united in the ideal monarch. He executes his own sentences. His acts are decisions. The psalmist has no thought of inferior officers by the king's side. One figure fills his mind and his canvas. Surely such an ideal is either destined to remain for ever a fair dream, or its fulfilment is to be recognised in the historical Person in whom God's righteousness dwelt in higher fashion than psalmists knew, who was, "first, King of righteousness, and then, after that, also King of peace," and who, by His deed, has broken every yoke, and appeared as the defender of all the needy. The poet prayed that Israel's king might perfectly discharge his office by Divine help; the Christian gives thanks that the King of men has been and done all which Israel's monarchs failed to be and do.