You may be thinking of Romans 11:26-27, “And so ALL ISRAEL SHALL BE SAVED: as it is written, There shall come out of Sion the Deliverer, and shall turn away ungodliness from Jacob: For this is my covenant unto them, when I shall take away their sins.”  To understand the Apostle Paul’s intention in quoting this verse from Isaiah, let’s read the entire verse.  Isaiah 59:20 tells us, “And the Redeemer shall come to Zion, and UNTO THEM THAT TURN FROM TRANSGRESSION in Jacob, saith the LORD.”  Paul is pointing out that this deliverance shall come to Jacob, or Israel.  However, we see from reading the entire quoted verse that this deliverance will come upon those who TURN FROM TRANSGRESSION.

Paul is not saying that every Jew of every age would be saved.  He had proved that a large portion of them would be, in his own time, rejected and lost. But the time would come when, as a people, they would be restored, or literally, when a REMNANT of the nation of Israel would turn to God; and then it could be said of them, that, as a nation, they were restored to the Lord’s favor.

This is speaking of a future day when the Lord will once again focus His attention on His earthly people, Israel.  The time is during the Tribulation period.  Let’s read of that day in Daniel 12:1, “And at that time shall Michael stand up, the great prince which standeth for the children of thy people: and there shall be a time of trouble, such as never was since there was a nation even to that same time: and at that time thy people shall be delivered, EVERY ONE THAT SHALL BE FOUND WRITTEN IN THE BOOK.” Those whose names are ‘written in the Book’ are those who have truly accepted and put their faith in the Lord Jesus Christ.  They recognize and acknowledge what most of the nation refuses…the Lord Jesus Christ is the promised Messiah of God.

Let’s consider the words of the Lord Jesus regarding Israel in Luke 13:34-35, “O Jerusalem, Jerusalem, which killest the prophets, and stonest them that are sent unto thee; how often would I have gathered thy children together, as a hen doth gather her brood under her wings, and ye would not! Behold, your house is left unto you desolate: and verily I say unto you, Ye shall not see me, until the time come when ye shall say, Blessed is he that cometh in the name of the Lord.”  The Lord’s desire was to save Israel, but they would not have Him.  Of the Lord Jesus, Israel had said, “We will not have this man to reign over us.” (Luke 19:14).  John 1:11 tells us, “He came unto his own, and his own received him not.”  However, in that coming day, the Lord will pour out His blessings upon those who will say, “Blessed is he that cometh in the name of the Lord.”  This is the real Israel of God, of whom it is written, “All Israel shall be saved.”  (355.2)