Verse 1
Psalms 129:1. Many a time have they — Namely, my enemies or oppressors; afflicted me from my youth — From the time that I was a people; when I was in Egypt, and after I came out of it, which is called the time of Israel’s youth, Jeremiah 2:2; Ezekiel 23:3. I am the people that has been oppressed more than any people, that has been as a speckled bird, pecked at by all the birds round about; attacked by all the beasts of the field assembled to devour, Jeremiah 12:9. It is true they brought their troubles upon themselves by their sins, for which it was that God punished them; but it was for the peculiarity of their covenant, and the singularities of their religion, that their neighbours hated and persecuted them. God’s real people have always had many enemies, and the state of the church, from its infancy, has frequently been an afflicted state.

Verse 3-4
Psalms 129:3-4. The ploughers ploughed upon my back — They not only threw me down and trod me under foot, but cruelly wounded, mangled, and tormented me, and had no more pity upon me than the plough-man hath upon the earth which he cuts at his pleasure. He saith, upon my back, either because they did literally scourge the captives upon their backs with such cords as are mentioned Psalms 129:4, although we do not read that the Israelitish captives were thus used by any of their enemies, or by way of allusion to that usage, which made a sort of furrows on the backs of those whom they thus scourged. They made long their furrows — They often repeated their injuries, and prolonged my torments. Thus, for our sakes, he who knew no sin gave his back to the smiters, (Isaiah 50:6,) and permitted those ploughers to make long their furrows upon it. But, (Psalms 129:4,) The righteous Lord cut asunder the cords of the wicked — Defeated their schemes and projects, frustrated their designs, and brought ruin on them by those very means whereby they endeavoured to effect the destruction of the rising church. Vengeance overtook the wretched instruments of the Messiah’s sufferings; and the persecutors of his servants, in all ages, shall perish in like manner, as the psalmist proceeds to assure us in the verses following.

Verses 5-8
Psalms 129:5-8. Let them all be confounded, &c. — Hebrew, יבשׁו ויסגו אחור, they shall all be confounded, and turned back — Forced to retreat with shame and disappointment. And so in the next verse, instead of Let them be, read, They shall be as grass upon the house tops — Which there were flat, and therefore more capable of grass, or green corn, growing between the stones than ours are; which withereth, &c. — Which, having no deep root, never comes to maturity. And so all their designs shall be abortive. Thus the enemies of God’s church wither of themselves, and stay not till they are rooted out by the judgments of God. Neither do they which go by — According to the ancient and laudable custom of saluting and praying for the prosperity of harvest labours; say, The blessing of the Lord be upon you, &c. — Which was a usual salutation given by passengers to reapers, as we see Ruth 2:4. If, in a similar way, we acknowledge God’s providence, testify our good-will to our neighbours, and commend their industry, our kind wishes will be accepted as pious ejaculations, if they come from devout and upright hearts. But religious expressions, being sacred things, must never be made use of in light and ludicrous actions. Mowing the grass on the house-top would be a jest, and therefore those that have a reverence for the name of God will not prostitute to such an action those forms of salutation which savour of devotion; for holy things must not be jested with.