Final answer:
The prophet Jehu prophesied against Jehoshaphat for joining with Ahaziah.
Step-by-step explanation:
In the Bible, the prophet Jehu prophesied against Jehoshaphat for aligning himself with Ahaziah. Jehoshaphat's partnership with Ahaziah, who was an unfaithful king, was seen as a betrayal of God's commandments. As a result, Jehu proclaimed that God would break Jehoshaphat's works or undertakings.