swift reckoning.
Not Biblical.
Muslim:
And God is swift at reckoning. (Quran, three:199)
I was thinking along the lines of "recompense", as in Isa 66.6
A voice of tumult from the city, a voice from the temple, the voice of the Lord rendering recompense to his enemies:
Deu 32.35. To me belongs vengeance, and recompense when their foot shall slip; for the day of their calamity is at hand, and the things that shall come upon them make haste: