Psalm 127:1 (BSB)

A song of ascents. Of Solomon. Unless the LORD builds the house, its builders labor in vain; unless the LORD protects the city, its watchmen stand guard in vain.

From Psalms 127. Also in the ESV.

Commentary on Psalm 127:1

• John Calvin (Reformed), Calvin's Commentaries on Psalm 127:1-5: PSALM 127 This Psalm shows that the order of society, both political and domestic, is maintained solely by the blessing of God, and not by the policy, diligence, or wisdom of men; and that the procreating of children is his peculiar gift. A Song of Degrees of Solomon. Psalm 127:1-2 1.
• C.H. Spurgeon (Reformed Baptist), The Treasury of David on Psalm 127:1: Except the Lord build the house, they labour in vain that build it. The word vain is the keynote here, and we hear it ring out clearly three times. Men desiring to build know that they must labour, and accordingly they put forth all their skill and strength; but let them remember that if Jehovah is not with them their designs will prove failures.
• Matthew Henry (Presbyterian), Matthew Henry's Complete Commentary on Psalm 127:1-5: We are here taught to have a continual regard to the divine Providence in all the concerns of this life. Solomon was cried up for a wise man, and would be apt to lean to his own understanding and forecast, and therefore his father teaches him to look higher, and to take God along with him in his undertakings.
• John Gill (Reformed Baptist), Exposition of the Old and New Testaments on Psalm 127:1: Except the Lord build the house, they labour in vain that build it,.... Whether it be understood literally of an artificial house, as Solomon's own house; or the house of the Lord, or any other: let a man be ever so bent upon building one, or have ever so much skill in drawing the plan of it, or be ever so well provided to go...