Psalm 128 verses 5-6

Today's verses of Psalm 128 take the form of a curse on the face of it, and so need to be considered in their proper context: these words a warning to repent, for repentance and salvation are always possible while we still have life!

Psalm 128 (129) – Saepe expugnaverunt me

Vulgate	Douay-Rheims
Canticum graduum.	A gradual canticle.
1 Sæpe expugnavérunt me a juventúte mea, * dicat nunc Israël:	Often have they fought against me from my youth, let Israel now say.
2  Sæpe expugnavérunt me a juventúte mea: * étenim non potuérunt mihi.	2 Often have they fought against me from my youth: but they could not prevail over me.
3  Supra dorsum meum fabricavérunt peccatóres: * prolongavérunt iniquitátem suam.	3 The wicked have wrought upon my back: they have lengthened their iniquity.
4  Dóminus justus concídit cervíces peccatórum: * confundántur et convertántur retrórsum omnes, qui odérunt Sion.	4 The Lord who is just will cut the necks of sinners: 5 Let them all be confounded and turned back that hate Sion.
5  Fiant sicut fœnum tectórum: * quod priúsquam evellátur exáruit:	6 Let them be as grass upon the tops of houses: which withers before it be plucked up:
6  De quo non implévit manum suam qui metit: * et sinum suum qui manípulos cólligit.	7 Who with the mower fills not his hand: nor he that gathers sheaves his bosom.
7  Et non dixérunt qui præteríbant: Benedíctio Dómini super vos: * benedíximus vobis in nómine Dómini.	8 And they that passed by have not said: The blessing of the Lord be upon you: we have blessed you in the name of the Lord.

Notes on the verses

5. Fiant sicut fœnum tectorum, quod priusquam evellatur exaruit:Let them be as grass on the tops of houses: which withered before it be plucked up

6. de quo non implevit manum suam qui metit, et sinum suum qui manipulos colligit. 

Wherewith the mower filleth not his hand: nor he that gathereth sheaves his bosom.  

Fiant (let them be) sicut (like) fœnum (grass) tectórum (on the rooftop) quod (that) priúsquam (before)

evellátur (it is pulled out) exáruit (it) withers

The image is of blades of wheat or corn growing on flat roofs that can never develop sufficient roots to harvest because the soil is too shallow and it lacks protection from the sun.

fio, factus sum, fieri (pass, of facio), to be made or done, to become, happen

foenum, i, n., grass.

tectum, i, n.  a roof, house top.

priusquam or prius quam, adv., before, before that.

evello, velli, vulsum, ere 3, to tear, pull, or pluck out.

exaresco, arm, escere 3, to become dry, to wither, dry up. 

De (from) quo (which) non (not) implévit (he does not fill) manum (hand) suam (his) qui (who/which) metit (he reaps et (and) sinum (breast) suum (his) qui (who/which) manípulos (sheaves) cólligit (he gathers)

The second phrase is difficult to translate. ‘Sinus’ normally means bosom or breast – some have suggested that the thought is probably that no bunch of grass is able to be gathered up against his breast in order to be tied into a sheaf.  Others though have suggested that sinus here refers to the fold of a garment where things can be tucked in, and the NETS Septuagint adopts this translation, making the verse 'With which no reaper filled his hand, and a gatherer of sheaves, the fold of his garment'.

impleo, plevi, pletum, ere 2  to fill, fill up, fill full;  to fill, to cover; to fill, satisfy.

manus, us, f.,  hand

meto, messiii, messum, ere 3, to reap, mow, gather harvest.

sinus, us, m.,  bosom, breast; the arm.

colligo, legi, lectum, ere 3 to gather, gather together, collect.

manipulus, i, m.  a small bundle, a handful; a sheaf. 

Isaiah's prophecy about the destruction of Sennacherib (2 Kings 19:26) uses the identical image of grass on a rooftop.  Bellarmine explains the extension of the metaphor:

Another imprecation, which, too, is to be read as a prediction, for it conveys to us the briefness of the happiness of the wicked, and, by a very happy idea, compares it to grass, a vile and fragile substance, and, as is said of it, "which is to day, and tomorrow will be cast into the fire;" and, not content with comparing it to grass, he adds, that it is like the grass that grows on the top of a house, a thing of no value, so much so that nobody ever thinks of cutting it, saving it, or making it into bundles, but leaves it where it grows to wither and to rot. 

He goes on to encourage us to ponder final judgment:

At present, we don't see the full extent of this comparison, though we know of nothing, perhaps, more worthless, or of less value than such grass; but when we shall all come to be judged we shall see that such a comparison, instead of being over the mark, is considerably under it. What will be, then, to see those who abounded in the riches and power of this world, and who imagined they had, through such riches, established themselves and their families in their kingdoms and empires, shoved out ignominiously, and hurled into the lowest pit? and, furthermore, to see those who had reveled in pleasures and enjoyments, who knew not how to put up with the slightest inconvenience, consigned to everlasting torments, without the slightest hope of the smallest relief for all eternity?

And you can find notes on the last verse of the psalm here.