Biblical References
In the culture of the Israelites, the rod would be a natural symbol of authority, as the tool used by the shepherd to correct and guide his flock (Psalm 23:4). Moses' rod is, in fact, cited in Exodus 4:2 as carried by him while he tended his sheep; and later (Exodus 4:20) becomes his symbol of authority over the Israelites (Psalm 2:9, Psalm 89:32, Isaiah 10:24 and 11:4, Ezekiel 20:37). The rods of both Moses and Aaron were endowed with miraculous power during the Plagues of Egypt (Exodus 7:17, 8:5, 8:16-17, 9:23, and 10:13); God commanded Moses to raise his rod over the Red Sea when it was to be parted (Exodus 14:16) and in prayer over Israel in battle (Exodus 17:9); Moses brings forth water from a stone using his rod (Exodus 17, Numbers 20:11).
Aaron's rod, however, is cited twice as exhibiting miraculous power on its own, when not physically in the grasp of its owner. In Exodus 7 (Parshat Va'eira in the Torah), God sends Moses and Aaron to Pharaoh once more, instructing Aaron that when Pharaoh demands to see a miracle, he is to "cast down his rod" and it will become a serpent. When he does so, Pharaoh's sorcerers counter by similarly casting down their own rods, which also become serpents, but Aaron's rod/serpent swallows them all. "Pharaoh's heart is stubborn" and he chooses to ignore this bit of symbolic warning, and so the Plagues of Egypt ensue. Notably, this chapter begins with God telling Moses, "Behold, I have made you as God to Pharaoh and your brother Aaron will be your prophet." As God transmits his word through his prophets to his people, so Moses will transmit God's message through Aaron to the pharaoh. The prophet's task was to speak God's word on God's behalf. He was God's "mouth". (Exodus 4:15-16)
In Numbers 17, Korah's rebellion against Moses' proclamation of the tribe of Levi as the priesthood has been quashed and the entire congregation's ensuing rebellion has resulted in a plague, ended only by the intercession of Moses and Aaron. In order to "stop the complaints" of the Israelites, God commands that each of the Twelve Tribes provide a rod; and only that of the tribe chosen to become priests will miraculously sprout overnight. Aaron provides his rod to represent the tribe of Levi, and "it put forth buds, produced blossoms, and bore ripe almonds" (Numbers 17:8), as an evidence of the exclusive right to the priesthood of the tribe of Levi. In commemoration of this decision it was commanded that the rod be put again "before the testimony" (Numbers 17:10). According to tradition, the rod of Aaron bore sweet almonds on one side and bitter on the other; if the Israelites followed the Lord, the sweet almonds would be ripe and edible, but if they were to forsake the path of the Lord, the bitter almonds would predominate. A later tradition asserts (Hebrews 9:4) that the rod was kept in the Ark of the Covenant. The main fact, however, is thus confirmed, that a rod was preserved in the Tabernacle as a relic of the institution of the Aaronic priesthood.
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