Theodore of Mopsuestia

Something of this kind is the meaning of the word oracle: in his wish to give the prophets an insight often productive of rapture, God caused a sudden transformation of their mind so that while in this condition they might receive the knowledge of the future with deeper fear. He calls it “oracle,” then, since the grace of the Spirit, as though suddenly taking hold of the prophet’s mind, transformed it with a view to the revelation of what was to be made clear. He is saying the same thing here too: “an oracle of Nineveh, a book of the vision of Nahum the Elkoshite,” as if to say, the prophet’s mind was suddenly seized by the grace of the Spirit and transformed so as to contemplate those things through which he learned of the fate of Nineveh and which he provided to his listeners as instruction in what was shown to him.