Canonical Gospels
The Diatessaon is an attempt at a Harmony of the four canonical Gospels. It was complied by Titian in about AD172, but it contains readings whihc imply that he used versions of the canonical gospels some of which contain pre markan elements. In an article published in the Back of Helmut Koester's Ancient Christian Gospels, William L. Petersen states: "Sometimes we stumble across readings which are arguably earlier than the present canonical text. One is Matthew 8:4 (and Parallels) where the canonical text runs "go show yourself to the priests and offer the gift which Moses commanded as a testimony to them" No fewer than 6 Diatessaronic witnesses...give the following (with minor variants) "Go show yourself to the priests and fulfill the law." With eastern and western support and no other known sources from which these Diatessaranic witnesses might have acquired the reading we must conclude that it is the reading of Tatian...The Diatessaronic read