Oral gospel traditions called the M source for Matthew and the L source for Luke, which may have been a mix of written and oral material (see Two-source hypothesis). Most scholars believe that the author of John's gospel used oral and written sources different from those available to the Synoptic authors – a "signs" source, a "revelatory discourse" source, and others – although there are indications that a later editor of this gospel may have used Mark and Luke. Oral transmission may also be seen as a different approach to understanding the Synoptic Gospels in New Testament scholarship. Current theories attempt to link
Gospel of Peter in the canonical gospels was transmitted orally, through readings in the churches, i.e. that the text is based on what the author "remembers" about the other gospels, together with his own embellishments. Ron Cameron and others have further speculated the Gospel of Peter was written independently of the synoptic gospels using an early proto-gospel. A consequence of this is the potential existence of a source text that formed the basis of the passion narratives in Matthew, Luke, and Mark, as well as in Peter. Origen makes mention of the Gospel of Peter as agreeing with the tradition of the Hebrews.