Revelations 13: 15-18
He was given power to give breath to the image of the first beast, so that it could speak and cause all who refused to worship the image to be killed. He also forced everyone, small and great, rich and poor, free and slave, to receive a mark on his right hand or on his forehead, so that no one could buy or sell unless he had the mark, which is the name of the beast or the number of his name. This calls for wisdom. If anyone has insight, let him calculate the number of the beast, for it is man’s number. His number is 666.
Revelations 14: 9-11
A third angel followed them and said in a loud voice: “If anyone worships the beast and his image and receives his mark on the forehead or on the hand, he, too, will drink of the wine of God’s fury, which has been poured full strength into the cup of his wrath. He will be tormented with burning sulfur in the presence of the holy angels and of the Lamb. And the smoke of their torment rises for ever and ever. There is no rest day or night for those who worship the beast and his image, or for anyone who receives the mark of his name. (which was 666)”
I saw thrones on which were seated those who had been given authority to judge. And I saw the souls of those who had been beheaded because of their testimony for Jesus and because of the word of God. They had not worshiped the beast or his image and had not received his mark on their foreheads or their hands. They came to life and reigned with Christ a thousand years.