The family of Shaphan, including Micaiah the son of Gemariah, held a close and special relationship with the prophet Jeremiah. Compared to the rest of the people, the members of this family stood out because they were much more willing to accept his prophetic messages [ביאור שטיינזלץ].
When Micaiah heard the messages being shared, he was listening to direct prophecies spoken through the Holy Spirit, which conveyed the exact words of God [מצודת דוד]. These divine declarations were not simply recited from memory. Rather, they were read aloud directly from the text written on the scroll [רד"ק, מצודת דוד].