[Costeon]

What, if any, apostolic doctrines are based on only one verse or passage?

I don't recall which thread it was, but posters were debating the idea that a doctrine must be supported by multiple passages, in particular the validity of the idea that there must be "two or three witnesses." Those against that, I believe, said something to the effect that God only had to speak once for something to be valid. If this is so, what are these teachings that God only spoke once about?