There was a lot of teaching person to person. Even Paul talks about it. It’s not all written down.
So what is it?
And how do we know?
How can we be sure of its veracity?
They were teaching in accordance with what was written. It was all of one accord. There were no contradictory revelations, teachings or traditions. Traditions in contradiction were condemned. The Gospel as taught by the Apostles was not to be strayed away from under threat of being accursed. It was itself written down and was scripture as well. Test every teaching, doctrine, belief and spirit against scripture, we are told to do this. That which is at odds or in contradiction is not of God.
Please show proof that what they taught “person to person” was different or not contained in the written word.