The assumption that Luke’s story [of the Prodigal Son] must be independent of Matthew’s overlooks the dynamic, generative nature of the Jesus tradition in its written embodiments. The dynamic of tradition would also be lost if we concluded that Luke and not Jesus is the author of the Prodigal Son and the Parable of the Lost Coin. That would be an utterly misleading claim. Luke composes these parables not as an independent author but as an interpreter, responsible for articulating the tradition that begins to form around Jesus during his ministry and that communicates him to ever-widening circles in the decades that follow, through preaching and writing. If oral and written tradition communicates Jesus, then it is also the case that Jesus communicates himself through the tradition. That is already so during his ministry, when certain traditions begin to take shape in response to the impulse proceeding from Jesus himself. From the start, he speaks through the medium of his own evolving tradition. This is why the gospels are so concerned to represent not only what Jesus does and says but also the range of responses he evokes. Yet in and through the reception process Jesus truly speaks—when, for example, a later evangelist finds in parables handed down by a predecessor the possibility of articulating anew the universal significance of his engagement with “tax collectors and sinners.” In the new text that results, it is still Jesus who speaks.
Watson, Francis. Gospel Writing: A Canonical Perspective (Eedermans, 2013). 208.