Albert Barnes Commentary Psalms 53:6

"Oh that the salvation of Israel were come out of Zion! When God bringeth back the captivity of his people, Then shall Jacob rejoice, [and] Israel shall be glad." — Psalms 53:6 (ASV)

Oh that the salvation of Israel ... - The only change here from Psalms 14:7 is that the word אלהים 'Elohiym — God, is substituted for “Jehovah,” Lord, and that the word rendered “salvation” is here in the plural. On the supposition that the psalm was adapted to a state of things when the city had been besieged, and the enemy defeated, this language would express the deep and earnest desire of the people that the Lord would grant deliverance.

It may also be supposed that at the time of such a siege, and while the Lord intervened to save them from the siege, it was also true that there was some general danger hanging over the people; that even the nation might be described as in some sense “captive;” or that some portions of the land were subject to a foreign power. The desire expressed is that the deliverance might be complete, and that the whole land might be brought to the possession of liberty and be rescued from all foreign domination. That time, when it should arrive, would be the occasion of universal rejoicing.