This Psalm is for Solomon, in which character the Lord builds the house, and we have the expression of the experience of the utter folly of all carnal Jewish expectations and efforts. They might have built the house, and great stones and buildings be there—it was in vain, the Lord did not own it. They might have watched the city, but they had awaked in vain—all had been in vain for Israel till the Lord arose and had mercy; then Jewish blessings flowed forth as upon earth in a posterity given as blessing in the Lord's peace.
This Psalm is the full experience of the Jews, after all their troubles, in entering into their Solomon rest. Many buildings of houses had there been, but all turned to nothing, and their glory was Babel. "Except Jehovah" the God of the Jews, of the earth in Solomon who did build the house—"build the house, in vain have its builders labored in it." It seems to me this has special reference to the labors of the Jews in the restoration of their temple which the Lord did not own—did not take the building of—for the place of His sanctuary shall be cast down. "Except the Lord keep the city," all their labors were in vain, for the city shall be taken and the houses rifled—toil and labor is alike vain to them—whereas, perhaps, "So to his beloved one he giveth sleep."
When there is the restoration this is its character—it is a new, fresh, prospective blessing, " Instead of thy fathers, thou shalt have children, whom " etc. He will make them houses.
4. "Children of the youth," I take to be "young men." It was not "Woe to them that be with child and to them that give suck in those days," for the Lord had built the city, the sons grew up as the plants, and their daughters as the polished corners of the temple. It was not now to say, "Blessed are the barren and the wombs that never bare"—the full blessing was come in—He made "the barren woman to keep the house, and to be a fruitful mother of children." Nor was it the prosperity of worldliness, as in Psa. 49, in the due time of sorrow, but the blessing from the Lord in the time of blessing, when the city was built, when the streets of Jerusalem, where the Lord Was, should be full of boys and girls playing, themselves blessing from the Lord. They were as arrows in the hand of the mighty man—His quiver was full of them, and He would speak with His enemies.