30 For we know him who said, “It is mine to avenge; I will repay,”a and again, “The Lord will judge his people.”b

Read Hebrews 10:30 Using Other Translations

For we know him that hath said, Vengeance belongeth unto me, I will recompense, saith the Lord. And again, The Lord shall judge his people.
For we know him who said, "Vengeance is mine; I will repay." And again, "The Lord will judge his people."
For we know the one who said, “I will take revenge. I will pay them back.” He also said, “The LORD will judge his own people.”