9 Then a third angel followed them, saying in a loud voice: "Whoever worships the wild beast and his statue and lets his mark be stamped on his forehead or on his hand,
Revelation 14:9 Cross References - Williams
Revelation 13:3-6
3 I saw that one of his heads seemed to have been mortally wounded, but its mortal wound had been healed. And the whole world was so amazed that they followed the wild beast,
4 and worshiped the dragon for giving the wild beast his authority; they also worshiped the wild beast, and said, "Who is there like the wild beast? Who is there to make war on him?"
5 Then there was given to the wild beast a mouth that uttered boastful, blasphemous words, and permission to wield his authority for forty-two months.
6 Then he opened his mouth to blaspheme against God, His name, and His dwelling place; that is, against those who live in heaven.
Revelation 13:11-17
11 Then I saw another wild beast coming up out of the land. He had two horns like a lamb, but he spoke like a dragon.
12 He exercises the full authority of the first wild beast in his presence; he makes the earth and its inhabitants worship the first wild beast, whose mortal wound had been healed.
13 He performs great wonders; even makes fire come down out of heaven to earth before men's eyes.
14 He leads the inhabitants of the earth astray because of the wonders he is permitted to perform in the presence of the wild beast, telling the inhabitants of the earth to erect a statue to the wild beast that bears the sword-thrust and yet has lived.
15 Permission has also been given him to impart life to the statue of the wild beast so that it can speak, and to have all who do not worship the statue of the wild beast killed.
16 And he makes all, great and small, rich and poor, freemen and slaves, have a mark stamped on their right hands or on their foreheads,
17 and he permits no one to buy or sell anything unless he bears the mark; that is, the name of the wild beast or the number that represents the name.
Revelation 14:6-8
6 Then I saw another angel flying in mid-air, with eternal good news to tell to the inhabitants of the earth, to every nation, tribe, language, and people.
7 He cried in a loud voice, "Fear God and give Him glory, because the hour of His judgment has come. Worship Him who made heaven and earth and sea and the springs of water."
8 Then a second angel followed, saying: "She has fallen! Mighty Babylon has fallen, who made all the nations drink the wine of vengeance due her immorality!"
Revelation 14:11
11 The smoke of their torture will go up forever and ever, and they will have no rest day or night -- those who worship the wild beast and his statue, and anyone who bears the mark of his name."