Deuteronomy 32:35
33 Their wine is snakes’ poison, the deadly venom of cobras. 34 “Is this not stored up with me?” says the Lord, “Is it not sealed up in my storehouses? 35 I will get revenge and pay them back at the time their foot slips; for the day of their disaster is near, and the impending judgment is rushing upon them!” 36 The Lord will judge his people, and will have compassion on his servants;62 when he sees that their power has disappeared, and that no one is left, whether confined or set free. 37 He will say, “Where are their gods, the rock in whom they sought security,
Hebrews 10:30
28 Someone who rejected the law of Moses was put to death without mercy on the testimony of two or three witnesses. 29 How much greater punishment do you think that person deserves who has contempt for the Son of God, and profanes the blood of the covenant that made him holy, and insults the Spirit of grace? 30 For we know the one who said, “Vengeance is mine, I will repay,” and again, “The Lord will judge his people.” 31 It is a terrifying thing to fall into the hands of the living God. 32 But remember the former days when you endured a harsh conflict of suffering after you were enlightened.
Notes and References
"... Many forms of divine retribution can fall on a human life which are worse than immediate death. In fact, Jeremiah made just such a complaint about the punishment inflicted on Jerusalem (Lamentations 4:6, 9). One might think also of King Saul, whose last days were burdened with such mental and emotional turmoil that death itself was a kind of release. 10:30-31. No one should regard such a warning as an idle threat. God Himself has claimed the right to take vengeance and to judge His people. In saying this, the author quoted twice from Deuteronomy (32:35-36), a chapter which most vividly evokes the picture of God's people suffering His retributive judgments (compare esp. Deuteronomy 32:19-27) ..."
Walvoord, John F. The Bible Knowledge Commentary: An Exposition of the Scriptures (p. 806) Victor Brooks, 1983