"They were reading whatever they had."
They were Jews in the Synagogue at Berea, Blogger. They were reading the Septuagint (not your later, different version of the OT).
I've got to bake the Vasilopita now. Have a Happy New Year!
Matthew wrote his gospel to the Jews. It is conceivable that they had such writing to compare with. Regardless, they read what they had. They compared Paul's words with Scripture and were commended for it. We have more books. We compare what is said with Scripture. Man's words mean nothing unless they are in alignment with Scripture.