Revelation 16:1

We had in the foregoing chapter the great and solemn preparation that was made for the pouring out of the vials; now we have the performance of that work. Here observe, I. That, though every thing was made ready before, yet nothing was to be put in execution without an immediate positive order from God; and this he gave out of the temple, answering the prayers of his people, and avenging their quarrel. II. No sooner was the word of command given than it was immediately obeyed; no delay, no objection made. We find that some of the best men, as Moses and Jeremiah, did not so readily come in and comply with the call of God to their work; but the angels of God excel not only in strength, but in a readiness to do the will of God. God says, Go your ways, and pour out the vials, and immediately the work is begun. We are taught to pray that the will of God may be done on earth as it is done in heaven. And now we enter upon a series of very terrible dispensations of Providence, of which it is difficult to give the certain meaning or to make the particular application. But in the general it is worth our observation that, 1. We have here a reference and allusion to several of the plagues of Egypt, such as the turning of their waters into blood, and smiting them with boils and sores.

— Matthew Henry's Concise Commentary (public domain)