'Foreheads' in the Bible

saying, "Do not damage the earth or the sea or the trees until we have sealed the slaves of our God on their foreheads."

And it was told to them that they should not damage the grass of the earth or any green [plant] or any tree, except those people who do not have the seal of God on their foreheads.

And I looked, and behold, the Lamb standing on Mount Zion, and with him one hundred forty-four thousand who had his name and the name of his Father written on their foreheads.

and they will see his face, and his name [will be] on their foreheads.