Ezekiel 38:17 - Ellicott's Commentary On The Whole Bible

Of whom I have spoken in old time. — This is put in that interrogative form which is often used for emphatic assurance. The word many before “years” is not in the original, but is correctly inserted to mark the accusative of duration. The statement is then an emphatic one, that God had of old and for a long time foretold by His prophets this attack of Gog. But the name of Gog is not mentioned in any earlier prophecy now extant, nor is it likely that any such, far less that any long series of such prophecies, have been lost. This concurs with many other indications in the prophecy to show that it does not relate to any particular event, but that Gog and his allies represent the enemies of the Church in general, and that the prophet is here depicting the same great and prolonged struggle between evil and good, between the powers of the world and the kingdom of God, which has formed the burden of so much of both earlier and later prophecy.