John Calvin Commentary Psalms 129:5

"Let them be put to shame and turned backward, All they that hate Zion." — Psalms 129:5 (ASV)

All who hate Zion shall be confounded, and tutored backward. Whether we take this as a prayer or a promise, the Prophet refers to the time to come. Since all the verbs are in the future tense, it is certainly a very appropriate interpretation to understand him as deriving instruction from past times about what is to be hoped for in the future, even to the end.

In whichever way we understand the passage, he declares that the faithful have no reason to be discouraged when they see their enemies raised on high. The grass that grows upon the housetops is not, because of its higher situation, more valuable than the blade of corn which in the low ground is trampled underfoot; for although it stands elevated above people’s heads, it is, in the first place, unprofitable, and secondly, it quickly withers away.

The verb, ףלש, shalaph, which we translate as comes forth, is by some rendered is plucked up. According to this translation, the sense is that without human hand or labor, the grass on the housetops is dried up. But as the verb properly signifies to be brought forth or to come forth, the meaning, in my opinion, is that the grass on the housetops, far from continuing long in a state of freshness, withers and perishes when it first springs up, because it has no root under it, nor earth to supply it with sap or moisture for its nourishment.

Whenever, then, the splendor or greatness of our enemies strikes us with fear, let us recall this comparison: just as the grass that grows upon the housetops, though high, is still without root and consequently short-lived, so too these enemies, the nearer they approach the sun through the height of their pride, will be all the sooner consumed by the burning heat, since they also have no root. For it is humility alone that draws life and vigor from God.