Ezekiel 9:2-4

2And behold, six men came from the way of the upper gate, which is turned toward the north, and every man [with] his slaughter weapon in his hand; and in the midst of them, one man clothed with linen, with a writer's ink-horn by his side; and they went in, and stood beside the brazen altar.

3And the glory of the 1God of Israel was gone up from the cherub, whereupon it was, to the threshold of the house; and he called to the man clothed with linen, who had the writer's ink-horn by his side;

4and Jehovah said unto him, Go through the midst of the city, through the midst of Jerusalem, and set a mark upon the foreheads of the men that sigh and that cry for all the abominations that are done in the midst thereof.