Jeremiah gathers a series of terrifying prophecies destined for Babylon, binding these harsh predictions of disaster into a single physical record [מצודת דוד, ביאור שטיינזלץ]. The act of writing everything down is mentioned first as a necessary setup. It prepares the way for a specific command that will follow, detailing exactly what must be done with the document [מצודת דוד].
The prophet records these events on a scroll [מצודת ציון]. The record is viewed from the perspective of its final, completed state. Only after the entire process of recording these severe warnings was finished did the scroll transform into a fully realized book [מצודת דוד].