The Presbyter Sabbatius, formerly a Jew, separates from the Novatians
Many, however, making no account of these events yielded to their own depravity; for not only did the Jews continue in unbelief after this miracle, but others also who love to follow them were shown to hold views similar to theirs. Among these was Sabbatius, of whom mention has before been made; who not being content with the dignity of presbyter to which he had attained, but aiming at a bishopric from the beginning, separated himself from the church of the Novatians, making a pretext of observing the Jewish Passover. Holding therefore schismatic assemblies apart from his own bishop Sisinnius, in a place named Xerolophus, where the forum of Arcadius now is, he ventured on the performance of an act deserving the severest punishments.
Reading one day at one of these meetings that passage in the Gospel where it is said, 'Now it was the Feast of the Jews called the Passover,' he added what was never written nor heard of before: 'Cursed be he that celebrates the Passover out of the days of unleavened bread.' When these words were reported among the people, the more simple of the Novatian laity, deceived by this artifice, flocked to him. But his fraudulent fabrication was of no avail to him; for his forgery issued in most disastrous consequences.
For shortly afterwards he kept this feast in anticipation of the Christian Easter; and many according to their custom flocked to him. While they were passing the night in the accustomed vigils, a panic as if caused by evil spirits fell upon them, as if Sisinnius their bishop were coming with a multitude of persons to attack them. From the perturbation that might be expected in such a case, and their being shut up at night in a confined place, they trod upon one another, insomuch that above seventy of them were crushed to death. On this account many deserted Sabbatius: some however, holding his ignorant prejudice, remained with him. In what way Sabbatius, by a violation of his oath, afterwards managed to get himself ordained a bishop, we shall relate hereafter.
Source: Ecclesiastical History (New Advent)