Cyprian, and the Bishops with him, first taught that it was necessary to purify by Baptism those converted from Heresy
First of all, Cyprian, pastor of the parish of Carthage, maintained that they should not be received except they had been purified from their error by baptism. But Stephen considering it unnecessary to add any innovation contrary to the tradition which had been held from the beginning, was very indignant at this.
Source: Church History (New Advent)