Malachi 4:1-6 KJV
1 For, behold, the day cometh, that shall burn as an oven; and all the proud, yea, and all that do wickedly, shall be stubble: and the day that cometh shall burn them up, saith the Lord of hosts, that it shall leave them neither root nor branch. 2 But unto you that fear my name shall the Sun of righteousness arise with healing in his wings; and ye shall go forth, and grow up as calves of the stall. 3 And ye shall tread down the wicked; for they shall be ashes under the soles of your feet in the day that I shall do this, saith the Lord of hosts. 4 Remember ye the law of Moses my servant, which I commanded unto him in Horeb for all Israel, with the statutes and judgments. 5 Behold, I will send you Elijah the prophet before the coming of the great and dreadful day of the Lord: 6 And he shall turn the heart of the fathers to the children, and the heart of the children to their fathers, lest I come and smite the earth with a curse.
Although the Old Testament ended with this passage, nothing changes at the beginning of the New Testament as far as Israel is concerned. The call to Israel as a nation continues through the Gospels, even though they end up crucifying Jesus Christ, who came to none but the lost sheep of the house of Israel. He asked the Lord to forgive them saying they know not what they have done. Even after the resurrection, he extends the offer to Israel all the way through the book of Acts until the Apostle Paul declares in Acts 28:28 that the salvation message is now sent (authorized) to the Gentiles and that they will hear it. At this time, Israel as a nation was set aside and became Lo-Ammi, which means not my people.
Israel will remain Lo-Ammi until Elijah returns and restores all things... which was the prophecy that was stated at the end of the Old Testament.