Peace be within thy bulwarks, etc. The two clauses express the same sentiment, and, therefore, the meaning of the first is gathered from the second. The term peace signifies nothing else than prosperity. The noun slvh, shalvah, in the second clause, sometimes signifies rest, but it is more frequently taken for abundance or prosperity On this account I have translated the noun vchylk, bechelech, within thy bulwark [1] I do not find fault with others who have translated it a ditch or outward wall; but the word bulwark agrees better with the word towers, which occurs at the close of the verse. The amount is, that David prays for the prosperity of the Church through its whole extent. Moreover, it is to be noticed, that when he offers supplication for its external prosperity, it is not to be understood as implying that he was unconcerned about its internal state or spiritual well being; but under the similitude of walls, [2] he wishes that on all sides the blessing of God may environ and fortify the holy city.

Footnotes

1 - Calvin's meaning is, that as the nouns peace and prosperity have a corresponding signification, he was of opinion, that there existed a similar correspondence between the other two nouns.

2 - The Latin copy here reads, "sed ad mores alludens;" but mores is evidently a typographical error for muros The French version has "mais sous ceste similitude des murs "

Peace be within thy walls - The word here rendered walls, means properly an host, an army; then a fortification, an entrenchment, especially the ditch or trench with the low wall or breastwork which surrounds it. Gesenius, Lexicon. It refers here to the fortifications or defenses around Jerusalem.
And prosperity - Peace; the same word which is used in the previous verse, and expressing the same idea - that of tranquility.
Within thy palaces - This word properly means a "fortress," "castle;" then, a palace, a residence of a king or a prince, 1-Kings 16:18; 2-Kings 15:25; Isaiah 25:2. The idea is, that such places abounded in Jerusalem; and the prayer is, that in those abodes of power, where the rulers of the land resided, there might be peace. The particular reason for this prayer is suggested in the following verse.

Peace be within thy walls - This is the form of prayer that they are to use: "May prosperity ever reside within thy walls, on all the people that dwell there; and tranquillity within thy palaces or high places, among the rulers and governors of the people."

Peace be within thy (f) walls, [and] prosperity within thy palaces.
(f) The favour of God prosper you both within and without.

Peace be within thy walls,.... The word say might be supplied; for this, with the following, seem to be petitions the psalmist puts into the mouths of those he desires to pray for Jerusalem's peace; and he directs them to pray in this manner, to take with them such words as these, and pray to the Lord. Jerusalem was a walled city, and so is the church of God; God himself is a wall of fire around her; salvation by Christ is as walls and bulwarks to her; the power and providence of God protect her: within these walls the people of God have a place and a name; all the inhabitants of Zion in common are included in this petition, and peace is wished for them all; let their condition and circumstances be what they may, be they high or low, rich or poor, stronger or weaker believers, children, young men, or fathers. Some render it, "in thine army", as the Targum, and other Jewish writers; in the church's militia, all saints being soldiers and in a warfare state; and here success to their arms against sin, Satan, and the world, is wished for;
and prosperity within thy palaces: as there were palaces in Jerusalem for the king, the nobles, and great men in the land; so there are in the church of God, where he is known, for a refuge; even the meanest places in it are preferable to the palaces of the greatest monarchs see Psalm 48:3, And here indeed all the saints are kings, and have their palaces; but particularly there are some who are set in the first place in the church, and over others in the Lord; who are their guides and governors, and are in office relation to the church as pastors and deacons now, as there were priests and Levites before: and the prosperity of these is to be prayed for, the good of the whole church being involved therein.