That Constantine, when a Youth, heard from him who wrote the Persecution Edict that the Righteous Men were the Christians
I call now on you, most high God, to witness that, when young, I heard him who at that time was chief among the Roman emperors, unhappy, truly unhappy as he was, and laboring under mental delusion, make earnest enquiry of his attendants as to who these righteous ones on earth were, and that one of the Pagan priests then present replied that they were doubtless the Christians. This answer he eagerly received, like some honeyed draught, and unsheathed the sword which was ordained for the punishment of crime, against those whose holiness was beyond reproach. Immediately, therefore, he issued those sanguinary edicts, traced, if I may so express myself, with a sword's point dipped in blood; at the same time commanding his judges to tax their ingenuity for the invention of new and more terrible punishments.
Source: Life of Constantine (New Advent)