| Barnes' Notes on the Bible I have declared - I have announced or predicted future events; I have warned of danger; I have marked out the path of safety. He had thus shown that he was the true God (see the note at Isaiah 41:22-23). And have saved - I have delivered the nation in former times of danger, and have thus shown that I would protect them. And have showed - Hebrew, 'Caused to hear.' I have made known future events, and have thus showed that I was God. When there was no strange god among you - Before the time when there was any idol in the nation, and when, therefore, it could not be pretended that deliverance was to be traced to anyone but to Yahweh. The word 'god' here is not in the original, but is properly supplied. The word זר zâr is evidently used instead of זר אל 'êl zâr, as in Psalm 44:20; Psalm 81:9. It denotes a god that is worshipped by foreigners. The sense is, that their former deliverance could in no sense be traced to any such foreign god. Therefore, ye are my witnesses - You who have so often been defended; you who have the predictions respecting future events, can be appealed to as evidence that I am the only true God, able to deliver. The doctrine taught in this passage is, that God may appeal to his dealings with his people as a demonstration that he is the true God, and that he is faithful and able to deliver - an appeal which may be made to his church at large in view of its trials, persecutions, and deliverances; and to every one who is his true friend and worshipper.
Clarke's Commentary on the BibleI have declared, and have saved - My prophets have always predicted your deliverances before they took place; and I have fulfilled their words to the uttermost.
Gill's Exposition of the Entire BibleI have declared, and I have saved, and I have showed,.... The Targum is, "I have showed to Abraham your father what should come to pass; I redeemed you out of Egypt, as I swore to him between the pieces; and I caused you to hear the doctrine of the law at Sinai.'' But the sense is, that God had declared by his prophets, long before the Messiah came, that he would send him; that he should come and save his people by his obedience, sufferings, and death; accordingly he was come, and was the author of salvation; the Lord had wrought out salvation by him, as he had declared he would; and this he had shown, published, and made known by the everlasting Gospel, preached among all nations: when there was no strange god among you; that assisted in this salvation; the arm of Christ alone wrought it out: or, "and this is not strange among you" (i); this work of salvation wrought out is not strange among you; it is well known unto you, being published in the Gospel. (i) "et non est in vobis alienum vel peregrinum", Musculus.
Geneva Study BibleI have declared, and have saved, and I have shewed, when there was no strange god among you: therefore ye are my witnesses, saith the LORD, that I am God.
Wesley's Notes 43:12 I - I first foretold your deliverance, and then effected it. When - And this I did when you did not worship any idols.
Jamieson-Fausset-Brown Bible Commentary12. declared-predicted the future (Isa 41:22, 23). saved-the nation, in past times of danger. showed-namely, that I was God. when . no strange god, &c.-to whom the predictions uttered by Me could be assigned. "Strange" means foreign, introduced from abroad.
Matthew Henry's Concise Commentary43:8-13 Idolaters are called to appear in defence of their idols. Those who make them, and trust in them, are like unto them. They have the shape and faculties of men; but they have not common sense. But God's people know the power of his grace, the sweetness of his comforts, the kind care of his providence, and the truth of his promise. All servants of God can give such an account of what he has wrought in them, and done for them, as may lead others to know and believe his power, truth, and love | 
