Plato differentiates knowledge from belief - though seemingly without any clear criteria as to how to distinguish the two beyond that knowledge concerns the Ideas and belief (even if derived via reason) does not and thus maybe true or false.
Among those things which he categorizes as belief are oracles/divination. While he doesn’t outright reject such divine revelation he (or whoever he has speaking) is wary of it and doesn’t claim to have knowledge of such things (if I’m recalling correctly).
On the other hand, he looks to the heavens and the rest of the material realm as imitations of the divine realm of the forms through which - via reason - we might obtain knowledge proper. The heavens are even explicitly constructed by the Demiurge for this purpose - that by observing the movements of the heavens we might learn to correct the disorder within our own souls and match our movements with the World Soul.
Since the heavens and the rest of the physical realm are composed in such a manner as to instruct us, is not all of the material realm itself divine revelation? And if so, is not the Philosopher who studies these things via reason to acquire knowledge and to share it an oracle/diviner?