Oh that the salvation of Israel were come out of Zion! when the LORD bringeth back the captivity of his people, Jacob shall rejoice, and Israel shall be glad.
Oh that the salvation of Israel were come out of Zion - literally, 'Who will give from Zion (the Lord's sanctuary) the salvation of Israel?' (namely, that promised in Psalms 14:4-7, through the destruction of Israel's foes). The mention of "Zion" is a covert plea before God, that, as reigning there the Theocratic Head of the kingdom, He cannot permit the enemy to triumph against the covenant people.
When the Lord bringeth back the captivity of his people - not that this psalm was written after the captivity. The phrase, 'bring back the captivity,' is a Hebrew idiom for restoring from depression, which is a figurative captivity (Psalms 142:7; Isaiah 42:7; Isaiah 49:9). So Job 42:10, "The Lord turned the captivity of Job." Job was never literally a captive (Ezekiel 16:53). The source of the phrase is Deuteronomy 30:3. Had the psalm been written during the captivity, the Psalmist could not have looked for salvation out of Zion, because the Shekinah symbol of God's presence had then left Zion (Ezekiel 11:22). Nor can Psalms 14:7 be a late addition, because it is found in Psalms 53:1-6; and the intentional seven-fold use of the name of "God" ("Lord") requires it. Hengstenberg translates х bªshuwb (H7725) ... shªbuwt (H7622)] 'And (oh that) the Lord returned to the captivity of his people.' The Hebrew х shuwb (H7725)] is ordinarily not transitive, 'bring back,' but intransitive, 'return.' The Chaldaic, Septuagint, Vulgate, Syriac, and Arabic, support the English version.
Jacob shall rejoice, and Israel shall be glad. The joyful thanksgiving which shall redound to God when He shall be pleased to save His people, is made a plea that He should do so.