The Lord the builder of the house and the keeper of the city.
(vv. 1-2) Already the godly remnant have owned that “If it had not been the Lord who was on our side,” they would have been swallowed up by their enemies. Looking back on their captivity they can say, “Blessed be the LORD...our soul is escaped” (Psa. 124:1, 6, 71<<A Song of degrees of David.>> If it had not been the Lord who was on our side, now may Israel say; (Psalm 124:1)
6Blessed be the Lord, who hath not given us as a prey to their teeth. 7Our soul is escaped as a bird out of the snare of the fowlers: the snare is broken, and we are escaped. (Psalm 124:6‑7)). Now they look on to the “house” and “the city,” the goal to which they are journeying, and they own, “Except the LORD build the house, they labor in vain that build it”; and “except the LORD keep the city, the watchman waketh but in vain.”
Thus, in the course of these pilgrim psalms, the godly own that it is the Lord who sets them free; it is the Lord who keeps them on their pilgrim journey; and it is the Lord who establishes them in the home to which they are going. They had seen the purpose of the Lord to have Jerusalem “builded” and “compact together” (Psa. 122:33Jerusalem is builded as a city that is compact together: (Psalm 122:3)). Now they recognize that only the Lord can carry out His purpose.
We know that in a day to come men will rebuild the temple; but the godly, guided by the Spirit of God, will realize that all the labors of men will be in vain. The Jewish nation, returning to the land in unbelief, will neither be able to maintain their temple or keep their city. However great the energy they may put forth, in rising up early and sitting up late, and eating the bread of sorrows―human efforts will be in vain.
In contrast to the restless energy of the flesh, the godly who trust in the Lord are kept in perfect calm, surrounded though they may be by sorrows and toil. In the midst of all human unrest, “He giveth His beloved sleep.”
(vv. 3-5) Further, the house and the city will not be complete without the inhabitants. If the Lord builds the house and keeps the city, He also gives “the children of youth” (JND) those who, with strength and vigor of youth, will be used under the hand of the Lord to defend the house and meet the enemy in the gate.