In the Book of Revelation, before seventh seal is broken, God commands His servants to be sealed for their protection.
“Then I saw another angel ascending from the east, having the seal of the living God. And he cried with a loud voice to the four angels to whom it was granted to harm the earth and the sea, Then I saw another angel ascending from the east, having the seal of the living God. And he cried with a loud voice to the four angels to whom it was granted to harm the earth and the sea, saying, “Do not harm the earth, the sea, or the trees till we have sealed the servants of our God on their foreheads. And I heard the number of those who were sealed. One hundred and forty-four thousand of all the tribes of the children of Israel were sealed” – Rev. 7:1-4