Ezekiel 9:4

and the Lord said unto him, Go through the midst of the city, through the midst of Jerusalem, the repetition of this expression indicating the thoroughness with which the work was to be done, every part of the city was to be reached, and set a mark upon the foreheads of the men that sigh and that cry for all the abominations that be done in the midst thereof. This mark, which come of the old Church fathers like to identify with that of the cross, since it. was the Hebrew letter tan, was a seal by which the wearers were to be securely guarded against special calamities about to be sent. They were the ones who were as yet deeply concerned about the increasing godlessness and were therefore to receive this consideration at the hand of the destroyer,