Albert Barnes Commentary 1 Kings 15:25

"And Nadab the son of Jeroboam began to reign over Israel in the second year of Asa king of Judah; and he reigned over Israel two years." — 1 Kings 15:25 (ASV)

The sacred historian now gives an account of the contemporary kings of Israel, beginning with Nadab, who ascended the throne in Asa’s second year, and concluding with Ahab, in whose fourth year Asa died. This narrative occupies the author almost to the close of the first Book of Kings.