Eze 9:4 And the Lord said to him: Go through the midst of the city, through the midst of Jerusalem: and mark Tau upon the foreheads of the men that sigh, and mourn for all the abominations that are committed in the midst thereof.
St. Ephrem of Syria ca. 306-373
“And mark a sign upon the foreheads of the men that sigh”, he says, for the circumcision of the flesh sufficed not unto salvation, and therefore has it been set aside, and the sign of the cross is substituted in its place” (T. ii. Syr. Comm. in Ezek.