I have not rewatched much and I prefer the Monster of the Week episodes, but I remember a scene from a Mythology episode in which Mulder does a quite theatrical reveal in which a document that someone wanted destroyed and lost to memory is passed via the oral tradition of a Native American tribe in perpetuity.

I cannot find any proof of it existing, nor can my friends, such that we are starting to fear Mandela Effect.

Can you help with at least the name of the episode if not a link to the scene itself?