I suspect that "text" there is an artefact of the translation-into-English -- it says "texts" and you think "written".
A simpler and more common translation is just, "found in the suttas and the vinaya".
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Instead, you ...
This is an inaccuracy in the translation of Ven. Sujato.
Let's compare it against the translation of Ven. Anandajoti on this page:
Sutte osāretabbāni Vinaye sandassetabbāni.
they should be laid
alongside the Discourses, they should be compared with the Discipline.
Here the latter translates "Vinaya" as "Discipline". The former ...