Amariah. The fifth high priest from Zadok (1 Chronicles 6:11), Jehoshaphat being the fifth king from David.
all matters of the LORD. Probably refers to spiritual, or ecclesiastical matters.
Deal courageously. be strong, and act.
Related Commentaries of 2 Chronicles 19:11
2 Chronicles 19:11
11 And, behold, Amariah the chief priest is over you in all matters of the LORD; and Zebadiah the son of Ishmael, the ruler of the house of Judah, for all the king's matters: also the Levites shall be officers before you. Deala courageously, and the LORD shall be with the good.