Matthew Poole and continuators on 1 Kings 14:1

AT that time Abijah the son of Jeroboam fell sick .

Either, First, Presently after the things described in the former Chapter: which, though related in the beginning of his Reign, yet might be done a good while after it, and so Ahijah the Prophet might be very old, as he is described to be, v. 4. Or, Secondly, many Years of it, i. e. Whilst Ieroboam lived and persisted in his former course. For this Phrase is oft used indefinitely, and without respect to the time last mentioned before it, as Dan. 12. 1. Matth. 4. 1.

By the stroke of God to punish Ieroboam's Rebellion against God.