דברי הימים ב, פרק י״ג, פסוק א׳

Tracking the kings of the divided kingdoms often relied on a synchronized timeline. Abijah takes the throne over Judah during the eighteenth year of Jeroboam's rule over Israel [ביאור שטיינזלץ]. This specific timing raises an interesting chronological puzzle. Jeroboam of Israel and Rehoboam, Abijah's father and predecessor in Judah, began their reigns in the exact same year. Since Rehoboam ruled for only seventeen years, a question arises regarding the transition of power: why did Abijah only become king in Jeroboam's eighteenth year, and was there a delay in his coronation?

One explanation suggests a straightforward sequence of events. Rehoboam died during his seventeenth year, and in the following year—which was Jeroboam's eighteenth—Abijah ascended the throne [מצודת דוד]. Conversely, another perspective argues that there was no gap or delay in the transfer of power in Judah. According to this view, Rehoboam did, in fact, live to enter his eighteenth year as king. However, because he died before completing it, that partial year was left out of his official record. Meanwhile, Jeroboam's count continued normally. Therefore, when Abijah took over immediately upon his father's death, the event was naturally recorded as taking place in the eighteenth year of the king of Israel [רד"ק].