Jeremiah 49:2

God testifies here plainly that he would not suffer the Ammonites for ever to enjoy their unjust plunder. He says that the days would come, in order to sustain with hope the minds of his children: for the Prophet announced his prediction at a time when the Ammonites were in a state of security; and then, some years elapsed while that people enjoyed their spoils. He therefore holds here the minds of the faithful in suspense, that they might learn patiently to wait until the fixed time of God’s vengeance came. For this reason, then, he says, that the days would come when God would cause the trumpet of war to resound in Rabbah He speaks as of a thing extraordinary, for the Ammonites thought, as we shall see, that they should never be in any danger. As, then, they proudly trusted in their own strength, the Prophet speaks here of the trumpet of war in Rabbah, which was the metropolis of the whole land. Some think that it was Philadelphia, a name given to it by Ptolemy. Interpreters, however, do not agree; but the opinion mostly received is, that it was Philadelphia. Now, as to the main thing, there is no doubt but that it was then the chief seat of government, and the capital of the kingdom, because the Prophet, stating a part for the whole, includes the whole land when he speaks of this city.

He says that she would become a heap of desolation But this was then wholly incredible, because Rabbah was so fortified that no one thought that it could be destroyed. But the Prophet now declares that the whole city would be demolished, so that neither walls nor private houses would remain, but that it would be a deformed mass of ruins. He adds, her daughters shall be burned with fire By daughters he no doubt understands towns and villages; and hence is confirmed what I have said, that Rabbah was then the chief city of the whole land of Ammon. At the end of the verse he says, Israel shall possess all who possess them By these words Jeremiah again confirms what I have slightly referred to, that the calamity of the Ammonites would be a testimony as to God’s paternal kindness towards his chosen people, because he resolved to avenge the wrongs done to them. As, then, God undertook the cause of the Israelites as his own, he sufficiently manifested the favor he had intended for his people, and for no other reason, but because he had gratuitously chosen them.