It is on all hands agreed that this verse is a prophecy of the conversion of the Gentiles. I will set a sign: by sign here some understand an ensign, as the word signifies, Psalms 74:4, which is a military sign to gather people together; by this may be understood Christ, Luke 2:34. See Isaiah 11:10. Or, as others, the ministry of the word attended with miracles (often called signs); these were set up among the Jews first, then among the Gentiles. Others (but less probably) understand by sign a mark of distinction, like that mentioned Ezekiel 9:4; so as, saith he, some shall escape and not be destroyed; and for those that shall escape, I will send them to Tarshish, Pul, Lud, Tubal, Javan, to Europe, Asia, and Africa, to all the quarters of the world, (see the Latin Synopsis, and the English Annotations, large discourses of these particular places,) to all nations that had never before heard of God or his true worship. And they shall declare my glory among the Gentiles; and they shall every where preach the gospel, and set up my gospel ordinances and institutions. This was eminently made good upon the apostles leaving the Jews, and turning to the Gentiles, Acts 13:46, and more fully after the destruction of Jerusalem, when the believers among the Jews, as well as the apostles, went about publishing the gospel to all people, which was the declaring of the Lord's glory.
Related Commentaries of Isaiah 66:19
Isaiah 66:19
19 And I will set a sign among them, and I will send those that escape of them unto the nations, to Tarshish, Pul, and Lud, that draw the bow, to Tubal, and Javan, to the isles afar off, that have not heard my fame, neither have seen my glory; and they shall declare my glory among the Gentiles.