The answer
In his treatment of the dispute over the validity of the baptism of the heretical Donatists, St. Augustine writes, “And this custom [i.e., the invalidity of their baptism], coming, I suppose, from apostolical tradition (like many other things which are held to have been handed down under their actual sanction, because they are preserved throughout the whole Church, though they are not found either in their letters, or in the Councils of their successors).”251
Fr. Tadros Yacoub Malaty
Notes
251 St. Augustine of Hippo, On Baptism, Against the Donatists 2.12 (NPNF I/4:430; PL 43:133).