'Ministering' in the Bible

But as for us, Jehovah is our God, and we have not forsaken him; and we have priests ministering unto Jehovah, the sons of Aaron, and the Levites in their work:

And it came to pass, when Jehu was executing judgment upon the house of Ahab, that he found the princes of Judah, and the sons of the brethren of Ahaziah, ministering to Ahaziah, and slew them.