וְהָיָ֣ה ׀ בַּיּ֣וֹם הַה֗וּא בְּי֨וֹם בּ֥וֹא גוֹג֙ עַל־אַדְמַ֣ת יִשְׂרָאֵ֔ל נְאֻ֖ם אֲדֹנָ֣י יְהוִ֑ה תַּעֲלֶ֥ה חֲמָתִ֖י בְּאַפִּֽי׃
And it shall come to pass in that day, when Gog shall come against the land of Israel, saith the Lord GOD, that My fury shall arise up in My nostrils.
Shulchan Arukh, Orach Chayim
3. We take out two Torah [scrolls]. From the first, we read "Look, you have been telling me..." [Exodus 33:12] and the maftir reads from the sacrifices corresponding to the possible day. The haftarah is from Ezekiel, "It will come to pass on the day that Gog comes..." [Ezekiel 38:18].