דברי הימים ב, פרק י״א, פסוק כ׳

The growth of Rehoboam's royal family brings significant complications regarding the rank of his wives and the future succession of the crown. The king marries Maacah, the daughter of Absalom, adding another woman from his own extended family to his household [ביאור שטיינזלץ].

Despite this union, Maacah's elevated position in the royal court and the eventual selection of her son as the heir are highly unusual. Because she was viewed as the daughter of an ordinary man, her natural social standing did not make her a likely candidate to become the king's chief wife. Furthermore, her son Abijah was born after the sons Rehoboam had already fathered with his previous wife, Abihail. Under standard rules of inheritance, a younger son born to a wife of lower initial standing would never be expected to take the throne in his father's place [מלבי״ם].