This reading is from the regular Torah portion for this week, Haazinu. The Torah portion for the second day of Rosh Hashanah is Genesis 22:1-24 and Numbers 29:1-6.
Lo, I raise My hand to heaven
And say: As I live forever,
When I whet My flashing blade
And My hand lays hold on judgment,
Vengeance will I wreak on My foes,
Will I deal to those who reject Me.
I will make My arrows drunk with blood--
As My sword devours flesh--
Blood of the slain and the captive
From the long-haired enemy chiefs.
O nations, acclaim His people!
For He'll avenge the blood of His servants,
Wreak vengeance on His foes,
And cleanse the land of His people.