In any case of texts this old reporting on traditions that were likely oral before being written down, it is impossible to know whether the author is an eyewitness or just a transcriber/copier of reports available to him. Even when the author claims to have witnessed the event himself, we cannot be sure he actually did, or that his claim of witnessing is not just the result of a direct copy from another text.
Or he just made it all up himself. Facts don't lie or have an agenda. Facts are just facts