But Moses said to the LORD, “Oh, my Lord, I am not eloquent, either heretofore or since thou hast spoken to thy servant; but I am slow of speech and of tongue.” Then the LORD said to him, “Who has made man’s mouth? Who makes him dumb, or deaf, or seeing, or blind? Is it not I, the LORD? Now therefore go, and I will be with your mouth and teach you what you shall speak.” But he said, “Oh, my Lord, send, I pray, some other person.” Then the anger of the LORD was kindled against Moses and he said, “Is there not Aaron, your brother, the Levite? I know that he can speak well; and behold, he is coming out to meet you, and when he sees you he will be glad in his heart. And you shall speak to him and put the words in his mouth; and I will be with your mouth and with his mouth, and will teach you what you shall do. He shall speak for you to the people; and he shall be a mouth for you, and you shall be to him as God. And you shall take in your hand this rod, with which you shall do the signs.”
Exodus 4:10-17

Aaron was the older brother of Moses and is considered to be the first High Priest from the Tribe of Levi. Aaron often spoke on behalf of his brother because of Moses’ “slow speech” (Ex. 4: 10-17). Aaron is depicted in Old Testament priestly vesture (Exodus Chapters 28 & 29), and holds a budding staff described in the Book of Numbers (17:1-13). He also holds a cruet of wine to symbolize the Eucharist.