Revelation 13:16-18

Revised Geneva Translation

¹⁶ And he made all - both small and great, rich and poor, free and enslaved - receive a mark on their right hand or on their foreheads;

¹⁷ so that no one could buy or sell unless he had the mark or the name of the beast or the number of his name.

¹⁸ Here is wisdom: Let him who has understanding count the number of the beast, for it is the number of a man. And his number is 666.