'Ministering' in the Bible

"Now as far as we're concerned, the LORD is our God, and we haven't abandoned him. The descendants of Aaron are ministering to the LORD as priests, and the descendants of Levi continue their work.

And that's exactly what happened. While Jehu was punishing Ahab's dynasty, he located the princes of Judah and the sons of Ahaziah's brothers who were ministering to Ahaziah, and he put them to death.