Question: If one prediction by a soothsayer proves correct, does that grant certain knowledge of the unseen?
Answer: No. A chance success or isolated true detail cannot acquire the status of revelation. Claims by soothsayers and diviners—especially those contrary to scripture and consensus—are not sources of creed.
وَلَا نُصَدِّقُ كَاهِنًا وَلَا عَرَّافًا
We do not affirm the claims of a soothsayer or diviner.
Follow-up: What role do the community and consensus play?
Clarification: The established scholarly consensus guards against baseless divergence, but an ordinary popular opinion should not automatically be called a binding consensus.