...before we find:
"It is written..." also including statements such as "thus saith the Lord," "the word of God/the Lord," "the Lord/God said," "the Law," the prophet..said," "Moses said..." "Scripture," "have ye not read.." etc., which are abundant , while the references to oral tradition are rare, and refer to contemporary teaching of Scriptural truths, the veracity of which being subject to testing by Scripture, (Acts 17:11) and do not refer to a body of historical passed-down ancient teachings, though Scripture can included instances of Truths from tradition as well as from pagans, as well as teachings from eyewitnesses and inspired remembrances of such.
Thus the argument is that since Scripture came out of oral tradition (though this is only partially true) as infallibly magisterially determined by Catholicism (but which is not the actual basis for its establishment and authority), then whatever else she says is inspired by God is also the word of God. Meaning that rather than the Spirit of Christ via His inspired writers making a difference btwn the chaff of oral tradition and the wheat, then the infallible, but not wholly inspired-of-God magisterium takes this place.
And how do we know Catholicism is this infallible magisterial authority? It cannot be first by Scripture, since Catholicism teaches one cannot assuredly correctly know what is of God apart from instruction from and faith in her, and thus appeal to Scripture in order to prove Catholicism is this infallible magisterial authority would be circular ("we know Scripture is true because Catholicism says so; and we know Catholicism is true because Scripture says so").
Thus when faced with this then the more experienced Catholic apologists resort to appealing to Scripture as merely being a reliable historical sources, and abstract altogether from their inspiration, which they purport establishes her claim to be that infallible magisterial authority, by reliance upon which one may also then be assured that Scripture (and whatever she channels out of her amorphous oral tradition) is the word of God.
However, what this means is that Catholics presume souls can discern that their (impure) church is of God but that they cannot discern the pure inspired words of God are just that until they assent to the former. Which position is simply untenable, for by the time of Christ a body of inspired writings of God had already been established, as is abundantly evidenced, which did not require an infallible magisterial authority to do so (nor was the inspired status of the writings the Lord and .NT invoked for support ever contended against by those who sat in the seat of Moses).
And of course, rather than Scripture establishing Catholicism's claim to be the one true church with an infallible magisterial authority, Catholic distinctives are not what is manifest in the only wholly inspired record of what the NT church believed (including how they understood the gospels).
And thus many novice Catholic apologists resort to the "we gave you the Bible = we are the infallible authority on what it is and means" argument, yet based upon that logic 1st century souls should have followed the historical magisterial stewards of Scripture (a body of which had been established) which sat in the seat of Moses.