Nicene and Post-Nicene Fathers, Vol. II:
City of God: Chapter 22

Chapter 22.—Of the Edict of Mithridates, Commanding that All Roman Citizens Found in Asia Should Be Slain.

These things, I say, I pass in silence; but I can by no means be silent regarding the order given by Mithridates, king of Asia, that on one day all Roman citizens residing anywhere in Asia (where great numbers of them were following their private business) should be put to death:  and this order was executed.  How miserable a spectacle was then presented, when each man was suddenly and treacherously murdered wherever he happened to be, in the field or on the road, in the town, in his own home, or in the street, in market or temple, in bed or at table!  Think of the groans of the dying, the tears of the spectators, and even of the executioners themselves.  For how cruel a necessity was it that compelled the hosts of these victims, not only to see these abominable butcheries in their own houses, but even to perpetrate them:  to change their countenance suddenly from the bland kindliness of friendship, and in the midst of peace set about the business of war; and, shall I say, give and receive wounds, the slain being pierced in body, the slayer in spirit!  Had all these murdered persons, then, despised auguries?  Had they neither public nor household gods to consult when they left their homes and set out on that fatal journey?  If they had not, our adversaries have no reason to complain of these Christian times in this particular, since long ago the Romans despised auguries as idle.  If, on the other hand, they did consult omens, let them tell us what good they got thereby, even when such things were not prohibited, but authorized, by human, if not by divine law.