Despite the fact that Tatian’s Diatessaron has not survived in its original form, its influence is clearly demonstrated by its extant translations into other languages and the influence that Diatessaron readings had on other text traditions. In the present article, Anton Baumstark finds a fascinating example of the latter case: a Gospel citation influenced by the Diatessaron tradition found in a Coptic Manichaean Kephalaia. The citation in question provides the text of the “good tree/bad tree” comparison found in Matthew 7 and Luke 6. However, a comparison of the wording found in the Coptic Kephalaia with the wording of these passages in Greek seems to indicate that the citation relies on a different textual tradition. When compared with the citation of this passage found in the writings of Aphrahat, who sometimes demonstrates knowledge of Diatessaron readings, and later Arabic and Latin translations of the Diatessaron, it seems likely that the source of the Coptic Kephalaia was influenced by the Diatessaron tradition.