No testimony is sufficient to establish a miracle, unless the testimony be of such a kind, that its falsehood would be more miraculous than the fact which it endeavors to establish.
— Hume's Maxim

From David Hume’s essay, “Of Miracles”.

He goes on to say that even in that case, you should subtract the two likelihoods to establish the level of assurance you can still have that the miracle took place.