"I shall return vengeance to My foes": These are the Cutheans, of whom it is written (Ezra 4:1) "And the foes of Judah and Benjamin heard that the people of the exile were building a sanctuary, etc."
"And I shall repay those who hate Me," viz. (Psalms 139:21-22) "Your haters, O L-rd, do I hate, and I strive with those who rise up against You. To the ends of hatred do I hate them; they have become my foes!"
(Devarim 32:42) "I will make My arrows drunk with blood": How is it possible to make arrows drunk? (The meaning is) rather: I shall make others drunk with what My arrows do.