דברי הימים א, פרק ט׳, פסוק ה׳

The genealogical records trace the lineage of the families belonging to the tribe of Judah. Within this tribal history, attention turns to the descendants of Shelah, Judah's son, who are known as the Shilonites [מצודת דוד, ביאור שטיינזלץ].

A central figure in this family line is Asaiah. By comparing historical records, it becomes clear that he is the exact same individual known as Maaseiah in the Book of Nehemiah [מצודת דוד, רלב״ג]. While his identity is recorded quite briefly in the current context, the parallel account in Nehemiah provides a deeper look into his family history, tracing his ancestry back through six generations [מלבי״ם]. Within his own immediate family, he is specifically recognized as the firstborn simply because he was the eldest of his brothers [מצודת דוד].