About this time the Novatians inhabiting Phrygia changed the day for celebrating the Feast of Easter. How this happened I shall state, after first explaining the reason of the strict discipline which is maintained in their church, even to the present day, in the provinces of Phrygia and Paphlagonia. Novatus, a presbyter of the Roman Church, separated from it, because Cornelius the bishop received into communion believers who had sacrificed during the persecution which the Emperor Decius had raised against the Church. Having seceded on this account, on being afterwards elevated to the episcopacy by such bishops as entertained similar sentiments, he wrote to all the churches
Christianity · Church History · Ecclesiastical History
Book IV, Ch. 28 — Of Novatus and his Followers. The Novatians of Phrygia alter the Time of keeping Easter, following Jewish Usage.
Ecclesiastical History · Socrates Scholasticus