Jeremiah 4:2

And thou shalt swear, &c. In taking a solemn oath, thou shalt appeal, not to dead and vain idols, but to Jehovah, the living and true God. This is put here for the whole worship of God, acknowledging and owning God as the only God, which is strongly expressed by this act: see Isaiah 48:1; Isaiah 65:16. In truth In sincerity, knowing that the matter of the oath is strictly true; in judgment Deliberately, advisedly, and reverently, the occasion being great and important; in righteousness That none be injured by it, that the things we engage to do, or to see done, be both lawful and possible, and that we look to the performance of our oaths. And the nations shall bless themselves in him This shall be a means of inducing the heathen nations to turn to the true God, and embrace the same way of worship. They shall think themselves happy to be incorporated with thee, that it may be with them according to the promise, Genesis 12:3. And in him, shall they glory Whereas before they gloried in their idols, they shall now glory in Jehovah alone. This is evidently “a prediction of gospel times, when the heathen should join with the Israelites in paying all solemn acts of worship and devotion to the true God only, and in ascribing all honour and glory to him, and to his only Son, the Messiah, in whom all the nations were to be blessed.”