That they may know thy way upon the earth. Here we have a clear prophecy of that extension of the grace of God by which the Gentiles were united into one body with the posterity of Abraham. The Psalmist prays for some conspicuous proof of favor to be shown his chosen people, which might attract the Gentiles to seek participation in the same blessed hope. By the way of God is meant his covenant, which is the source or spring of salvation, and by which he discovered himself in the character of a Father to his ancient people, and afterwards more clearly under the Gospel, when the Spirit of adoption was shed abroad in greater abundance. [1] Accordingly, we find Christ himself saying, "This is life eternal, that they might know thee the only true God," (John 17:3)

Footnotes

1 - "The petition here offered is, that the Gospel, God's way,' might be universally spread; -- a prayer that is not yet accomplished, but is in progress towards completion. The mention of nations and peoples, all of them, intimates, that the time which is the object of supplication is the time when God will no longer be the God of the Jews, but of the Gentiles also." -- Walford.

That thy way may be known upon earth - The law of God; the principles and methods of the divine administration; the way in which God rules mankind and in which he bestows his blessings on people. The prayer is, that all the earth might be made acquainted with the methods in which God deals with his people, or confers favors on people. The happiness of man depends on a knowledge of the principles on which God bestows his favors; for all people are, in all things, dependent on him. The success of a farmer depends on his understanding, and complying with, the laws and principles on which God bestows a harvest; the preservation of health, the restoration of health when we are sick, depends on a knowledge of the great laws which God has ordained for the continuance of the healthy functions of our bodies, and on the use of the means which he has provided for restoring health when those functions are disordered; and, in like manner, the salvation of the soul depends on the right understanding of the method which God has appointed to secure his favor. In neither of these cases - in no case - is it the business of people to originate laws of their own; laws for the cultivation of the earth, or for the preservation of health, or for the saving of the soul. The business of man is to find out the rules in accordance with which God bestows his favors, and then to act in obedience to them. The psalmist here supposes that there are certain rules or principles, in accordance with which God bestows blessings on mankind; and he prays that those rules and principles may be everywhere made known upon the earth.
Thy saving health among all nations - The original word here rendered "saving health," is "salvation." It is with great uniformity so rendered. It is indeed translated "welfare," in Job 30:15; help, in Psalm 3:2; Psalm 42:5; deliverance, in Psalm 18:50; Psalm 44:4; Isaiah 26:18; helping, Psalm 22:1; and health, in Psalm 42:11; but elsewhere it is in all cases rendered "salvation." The words "saving health" were adopted from an older version, but no argument should be founded on, them. The word "salvation" expresses all that there is in the original; and the prayer is, that the method by which God confers salvation on people may be made known throughout all lands. Assuredly no more appropriate prayer could be offered than that all the race may be made acquainted with the way in which God saves sinners.

That thy way may be known - That thy will, thy gracious designs towards the children of men, thy way of reconciling them to thyself, of justifying the ungodly, and sanctifying the unholy, may be known to all the nations upon the earth! God's way is God's religion; what he walks in before men; and in which men must walk before him. A man's religion is his way of worshipping God, and going to heaven. The whole Gospel is called this way, Acts 19:9.
Thy saving health - ישועתך yeshuathecha, "thy salvation." The great work which is performed in God's way, in destroying the power, pardoning the guilt, cleansing from the infection, of all sin; and filling the soul with holiness, with the mind that was in Christ. Let all nations - the whole Gentile world, know that way, and this salvation!

That (b) thy way may be known upon earth, thy saving health among all nations.
(b) That both Jews and Gentiles may know God's covenant made with them.

That thy way may be known upon earth,.... God's way and method of grace, in the salvation of sinners; the contrivance of it in Christ, the impetration of it by him, and the application of it by his Spirit; and the way of sinners to him through Christ, the way, the truth, and the life, the new and living way to the Father; and the way of life and salvation, which is grace, and by Christ alone; and the Gospel which points out this way, and is itself called the way of God, Acts 18:25; together with the ordinances of it, which are ways of pleasantness, and paths of peace; all this was made known by the apostles and first preachers of the Gospel; not only in the land of Judea, but throughout the whole earth;
thy saving health among all nations; or "thy salvation"; or "thy Jesus" (l); whose name signifies a Saviour; and who is the only one, and an able and willing one, and is God's salvation, of his appointing, promising, and sending; salvation is by him, and by him only; he came to obtain it, and he is the author of it; health is also by him, he is the physician of souls, and his blood the balm that cures every disease; so that he is the Saviour, salvation, and saving health, to his people; this was unknown to the nations of the world until the Gospel came among them, until the grace of God bringing this salvation appeared unto them, and shone upon them, Titus 2:11.
(l) "salutem tuam", Pagninus, Montanus, &c. "i.e. salvatorem cujus nomen erit Jesus", Gejerus.

thy way--of gracious dealing (Isaiah 55:8), as explained by--
saving health--or literally, "salvation."

Thy way - The way of truth, or the true religion; the same which in the next clause is called his saving health, and both together signify the way of salvation; deal so graciously with thy people, that thereby the Gentile - world may at last be allured to join with them.