At the first view this may seem hard; for we know how cruelly that miserable people had been treated by the Chaldeans. Then to pray for the most savage enemies, might have appeared unreasonable and by no means suitable. But the Prophet mitigates the hardness of the work by saying, that it would be profitable to them to pray for the happy condition of Babylon, inasmuch as they were the associates of their fortune. We know how much the prospect of what is profitable avails to persuade us, as we think not of undertaking anything except what we deem will be successful. For this reason then the Prophet teaches the Jews that they ought not to refuse what was required from them, when God bade them to pray for Babylon, because the prosperity of that kingdom would be for their benefit, he intimates also, as I have already hinted, that they were so connected with
Babylon, that they could not expect to be exempt from all trouble and annoyance, if any adversity happened to Babylon, for they were of the same body. We now perceive the meaning of the Prophet.
But we may hence deduce a very useful doctrine, -- that we ought not only to obey the kings under whose authority we live, but that we ought also to pray for their prosperity, so that God may be a witness of our voluntary subjection. For if it was the duty of the Jews to pray for the wellbeing of the Chaldeans for this reason, because they were for a certain time under their authority, there is no excuse for us, when we live under any legitimate prince, and that not only for a few days, unless we testify our voluntary submission before God; and he who prays to God for the happy state of the country in which he lives, will not surely neglect his other duties.  The principal thing indeed is to testify before God what our feeling is; and then other things must be added, such as promptitude to perform all duties of obedience and everything of the like kind. It now follows, --
 To pray for the peace of a city or country, and for the health or eternal salvation of rulers, is very different from wishing success to their ambitious, rapacious, or sanguinary undertakings; though this distinction is not generally attended to." -- Scott.