Two Reformed affirmations — Scripture's full substance; no equal unwritten word
Two affirmations follow.
First: everything belonging to the substance of faith and religion is fully and sufficiently in sacred Scripture.
Second: besides Scripture there is no word of God that is our faith's principle and rule — so no unwritten traditions equal Scripture's authority, and least of all Rome's so-called Apostolic and divine traditions.
The first follows from the second: if there is no divine word outside Scripture, Scripture must hold all that faith and salvation require, or we already lack necessities and have no sure path of salvation.
So, without rehearsing Scripture's own fullness-texts, the main proof target is this: no living-voice-only word of God stands as a certain faith-rule alongside Scripture.
Latin
XXV. Duo igitur affirmamus. Et primo quidem omnia quae pertinent ad substantiam fidei & religionis plene & sufficienter in Scriptura sacra contineri. Deinde, praeter Scripturam non extare ullum Dei verbum quod fidei nostrae sit principium & regula, adeoque nullas traditiones non scriptas aequalis esse cum sacra Scriptura authoritatis. Minime vero istud honoris tribuendum esse traditionibus illis quas Ecclesia Romana tanquam Apostolicas & divinas commendat. Prius autem illud sequitur ex posteriori. Etenim si nullum sit praeter Scripturam Dei verbum, necesse est illam omnia ad fidem & salutem necessaria continere, vel nos jam aliquibus necessariis carere. Et quod inde sequitur, nullam certam ad salutem nobis superesse viam. Itaque omissis iis testimoniis quibus Scriptura suam ipsius plenitudinem & perfectionem commendat, illud praecipue probare contendemus nullum esse Dei verbum viva voce tantum traditum quod cum Scriptura sacra certa sit fidei regula.