Psalm 121, verses 7-9

7	V	Fiat pax in virtúte tua: * et abundántia in túrribus tuis.
	NV	Fiat pax in muris tuis, et securitas in turribus tuis! ”.
	JH	Sit pax in muris tuis : abundantia in domibus tuis.
	Sept	γενέσθω δὴ εἰρήνη ἐν τῇ δυνάμει σου καὶ εὐθηνία ἐν ταῖς πυργοβάρεσίν σου

Text notes:  The Hebrew is closer to palaces here rather than towers in meaning.

virtus, utis, strength, power, might; an army, host; the angels.; the heavenly bodies, the sun, moon, and stars

turris, is,,  a tower; a palace.

DR	Let peace be in your strength: and abundance in your towers.
MD	Peace be within thy ramparts, and repose within they towers
Brenton	Let peace, I pray, be within thine host, and prosperity in thy palaces.
Cover	Peace be within thy walls, and plenteousness within thy palaces.
Grail	May peace reign in your walls, in your palaces, peace!"

St Robert Bellarmine interprets this verse as instructions on what we should pray for in relation to the Church:

He dictates the very words in which those who pray for peace and abundance to Jerusalem are to salute her. When you salute her say ye, "Let peace be in thy strength, and abundance in thy towers;" that is to say, may your walk be always secure and fortified, thereby ensuring perfect peace and quiet to all who dwell within them; "and abundance in thy towers;" no lack of meat or drink in your public buildings and private houses. 

8	V	Propter fratres meos, et próximos meos, * loquébar pacem de te:
	NV	Propter fratres meos et proximos meos loquar: “ Pax in te! ”.
	JH	Propter fratres meos et amicos meos loquar pacem tibi.
	Sept.	ἕνεκα τῶν ἀδελφῶν μου καὶ τῶν πλησίον μου ἐλάλουν δὴ εἰρήνην περὶ σοῦ

Text notes:  The Vulgate puts the second phrase in the imperfect (I was speaking peace of you); the Neo-Vulgate changes it to ‘Peace [be] within you’ to match the Hebrew.

propter, prep, with ace. In stating a cause: on account of, by reason of, because of, from, for, for the sake of.

frater, tris, m.  a brothe;  a fellow-man, kinsman, one of the same tribe; in the pi., usually rendered brethren. proximus, i, m., neighbor, friend, fellowman

loquor, locutus sum, loqui, to speak, utter, tell

DR	For the sake of my brethren, and of my neighbours, I spoke peace of you
MD	In behalf of my brother and my friends, I bespeak thee peace
Brenton	For the sake of my brethren and my neighbours, I have indeed spoken peace concerning thee.
Cover	For my brethren and companions’ sakes, I will wish thee prosperity.
Knox	For love of my brethren and my familiar friends, peace is still my prayer for thee;
Grail	For love of my brethren and friends I say: "Peace upon you."

This is a call to unity, Cassiodorus points out:

"He proclaims peace and denotes the signs of his peace as perfect men do. He says that he has proclaimed the peace of the Church for the sake of his brethren and neighbours, so that once instructed by this virtue of concord, they may love and seek unity. So he carried out his own teaching; through love of his brethren he proclaimed what he knew would be of benefit to all. So his message is that a person should not teach for his own praises or benefits, but should toil with merciful heart for the sake of brethren and neighbours."

St John Chrysostom's take on theme has a particularly contemporary relevance:

"After saying For the sake of my brethren and my neighbors, he wanted to show that he was praying for this not on account of their worthiness but rather that he might do them a favor, so he added For the sake of the house of the Lord our God, that is, I pray for peace for the sake of his glory so that his worship may once more return and instruction become more widespread."

9	V	Propter domum Dómini, Dei nostri, * quæsívi bona tibi.
	NV	Propter domum Domini Dei nostri exquiram bona tibi.
	JH	Propter domum Domini Dei nostri quaeram bona tibi.
	Sept	ἕνεκα τοῦ οἴκου κυρίου τοῦ θεοῦ ἡμῶν ἐξεζήτησα ἀγαθά σοι

domus, us,  a house, structure

quaeso, ivi or ii, ere 3 to beg, pray, beseech, entreat

bonus, a, um, good;  pleasant; upright  good things, possessions, prosperity.

DR	Because of the house of the Lord our God, I have sought good things for you.
MD	In behalf of the house of the Lord our God, I seek thee good.
Brenton	Because of the house of the Lord our God, I have diligently sought thy good.
Cover	Yea, because of the house of the Lord our God, I will seek to do thee good.
Grail	For love of the house of the Lord I will ask for your good.

St Augustine comments: 

"This solid city is the Church. Christ is the cement that binds it together. On earth, when the cement is poured, the walls are built up and the weight of the wall presses down to where the foundation has been laid. But if our foundation—Christ—is in heaven, then let us build up to heaven. In the basilica you see before you, in which we are gathered together today, the architects spread the cement to build from the ground up; but when we are re­made as a spiritual temple, the cement is poured upon us from on high. Let us make haste, then, to that place; let us run on until our feet are walking in your shadows, Jerusalem"

Psalm 121: Laetatus sum

Vulgate	Douay-Rheims
Canticum graduum.
1  Lætátus sum in his, quæ dicta sunt mihi: *  In domum Dómini íbimus.	I rejoiced at the things that were said to me: We shall go into the house of the Lord.
2  Stantes erant pedes nostri, * in átriis tuis, Jerúsalem.	2 Our feet were standing in your courts, O Jerusalem.
3  Jerúsalem, quæ ædificátur ut cívitas: * cujus participátio ejus in idípsum.	3 Jerusalem, which is built as a city, which is compact together.
4  Illuc enim ascendérunt tribus, tribus Dómini: * testimónium Israël ad confiténdum nómini Dómini.	4 For thither did the tribes go up, the tribes of the Lord: the testimony of Israel, to praise the name of the Lord.
5  Quia illic sedérunt sedes in judício, * sedes super domum David.	5 Because their seats have sat in judgment, seats upon the house of David.
6  Rogáte quæ ad pacem sunt Jerúsalem: * et abundántia diligéntibus te:	6 Pray for the things that are for the peace of Jerusalem: and abundance for them that love you.
7  Fiat pax in virtúte tua: * et abundántia in túrribus tuis.	7 Let peace be in your strength: and abundance in your towers
8  Propter fratres meos, et próximos meos, * loquébar pacem de te:	8 For the sake of my brethren, and of my neighbours, I spoke peace of you.
9  Propter domum Dómini, Dei nostri, * quæsívi bona tibi.	9 Because of the house of the Lord our God, I have sought good things for you.

And for notes on Psalm 122, go here.