John Gill Commentary Ezekiel 39:1

"And thou, son of man, prophesy against Gog, and say, Thus saith the Lord Jehovah: Behold, I am against thee, O Gog, prince of Rosh, Meshech, and Tubal:" — Ezekiel 39:1 (ASV)

Therefore, you son of man, prophesy against Gog As he had been ordered to do before, and must still continue to do it:

behold, I am against you, O Gog; which is repeated for the confirmation of it, and to inject terror into him; for terrible it is to have God against any:

the chief prince of Meshech and Tubal; (See Gill on Ezekiel 38:2), the Septuagint version adds "Ros" here as there.