Jeremiah 44:26

Hear ye now, he says, the word of Jehovah, etc. By these words, as I have already hinted, he intimates, that they could gain nothing by their insolence, except that they would thereby provoke God, who on the other hand did set up his own power against them. Thus, then, saith Jehovah, Behold, I have sworn by my great name, etc. As they had so often disregarded God speaking to them, he confirmed by an oath what he was going to say. Had he only threatened, they might have as usual disregarded him, as though the Prophet spoke what was vain. This is the reason why he now introduces God as making an oath. And it ought to be observed, that whenever God confirms his words by an oath, this he does, either because he sees that he has to do with men who are like stones, who cannot be made to feel by simple truth; or when he is pleased to give aid to our infirmity and sloth: for God confirms threatenings as well as promises by an oath. When he thus confirms threatenings, then he indirectly condemns the obstinate wickedness of those whom he addresses. But when he promises anything by an oath, he shews how great our propensity is to indulge doubts, and what weakness there is in our faith; for were such faith in us as ought to be, we should be contented with one little word. As, then, God interposes his own name as a pledge, it hence appears, that we are naturally unbelieving, or that the weakness of our faith is such that it wants this support. But here, as God threatens, he shews that the Jews were so obstinate in their wickedness, that it was necessary to shake them by terror.

Now, God makes an oath by his own great name Men, as the Apostle says, swear by God, (Hebrews 6:16;) because he is called as a witness and a judge when his name is interposed. But it is no superfluous addition, when God not only swears by himself, but by his own great name For he thus intimated, that the Jews were greatly deceived, if they thought that God would not execute vengeance on them, because they indulged themselves. For it is a common thing with hypocrites to measure God by their own judgment; and when they extenuate his power, they think of him as of a child. In order, then, to divest the Jews of this false imagination, he says, by his own great name There is, then, implied here a contrast between the greatness of God’s name, which cannot be diminished at the will of man, and the presumption of the ancient people, who rendered God’s name contemptible.