Oh, we can test your thesis from the bible itself.
Unless you can show where in the Old Testament the "word" was given to Simeon at the Temple that he would not see death until his eyes beheld Christ, your thesis fails utterly.
Luk 2:25 And, behold, there was a man in Jerusalem, whose name [was] Simeon; and the same man [was] just and devout, waiting for the consolation of Israel: and the Holy Ghost was upon him.Luk 2:26 And it was revealed unto him by the Holy Ghost, that he should not see death, before he had seen the Lord's Christ.
Luk 2:27 And he came by the Spirit into the temple: and when the parents brought in the child Jesus, to do for him after the custom of the law,
Luk 2:28 Then took he him up in his arms, and blessed God, and said,
Luk 2:29 Lord, now lettest thou thy servant depart in peace, according to thy word:
Luk 2:30 For mine eyes have seen thy salvation...
So in summation, a man speaking by the Holy Spirit refers to a revelation given to him personally and refers to that revelation, which appears no where in the scripture up to that point, as "thy word" while praising God.
This definitively disproves the contention that God's Word, and thus, authority, are restricted to the written scripture, alone. And it does so using nothing but written scripture, thus obligating those who profess Sola Scriptura to yield.