The Bereans were known for checking the Scriptures which would have been the OT (and possibly other writings outside of our OT) when it came to Paul’s claims
If the Bereans were to check Paul in this verse
“and all drank the same spiritual drink. For they drank from the spiritual Rock that followed them, and the Rock was Christ.” 1 Corinthians 10:4
Where would they look to justify his words. What rock is he referring to, how did it follow and what water did it give forth as drink?