YHWH purposed to make Moses “God” to Pharaoh and his brother Aaron his “prophet.” In his role as “God” to Pharaoh, Moses would represent YHWH, speak the words he revealed to him, and do everything he commanded. As Moses’ prophet, Aaron would relate and act according to the messages that his brother received from YHWH. Moses was to speak everything that YHWH commanded him, and Aaron would then tell Pharaoh everything, with the main message being that Pharaoh should permit the Israelites to leave Egypt. (7:1, 2)
YHWH knew beforehand that Pharaoh would defiantly refuse to obey. By allowing him to become obstinate, YHWH hardened his heart or his disposition and used the time during which Pharaoh manifested his stubborn attitude to perform impressive signs and wonders in Egypt, revealing himself to be the Supreme Sovereign whose will could never be successfully resisted. YHWH determined to lead his people out of Egypt subsequent to inflicting severe judgments upon the Egyptians. After he “stretched out [his] hand,” or directed his power, against the Egyptians and liberated his people from enslavement, they would “know” or be forced to recognize him as YHWH, the Almighty God, and their own gods and goddesses as powerless to help them. (7:3-5)
Moses and Aaron did everything YHWH commanded them to do. At the time of their speaking to Pharaoh, Moses was 80 years old and Aaron was 83. (7:6, 7) There were times when Aaron’s speaking was accompanied by his use of the rod that Moses had used as a shepherd. When Aaron held it and was directed to use it, this rod is identified as Aaron’s rod.
Upon Pharaoh’s asking for a (sign or [LXX]) wonder, YHWH directed that Moses tell Aaron to take his rod and throw it down on the ground before Pharaoh (“and before his servants” [or officials in the court]). It would then become a serpent (dragon [LXX]). Moses and Aaron did what they had been commanded, Aaron threw down his rod, and it turned into a serpent (dragon [LXX]). In response, Pharaoh summoned his sages and sorcerers or magicians. Resorting to their secret arts, these men threw down their rods and they became serpents (dragons [LXX]). Aaron’s rod, however, swallowed up their rods, establishing the superiority of the wonder that he performed. The Exodus account does not reveal whether the magicians seemingly duplicated the wonder through slight of hand or by holding the serpents in a manner that made them stiff and look like a rod until they were cast down. (7:8-12; see the Notes section regarding the comments of Josephus about this incident and also that of Targum Jonathan concerning the magicians.)
Despite witnessing what the “rod of Aaron” had done, Pharaoh continued to have a hardened heart or stubbornly to resist letting the Israelites leave. As YHWH had revealed to them beforehand, Pharaoh refused to listen or heed what Moses and Aaron said. YHWH then instructed them to take along the rod that had been turned into a serpent and to wait for Pharaoh at the edge of the Nile the next morning, at which time he would be arriving. (7:13-15) The Exodus account does not explain why Pharaoh would come to the Nile in the morning. Targum Jonathan says that he did this to “observe divinations at the water as a magician.” Another reason, in view of the importance of Nile flooding to supply water for irrigation, could be that Pharaoh may have been on an inspection tour to see the level of the river.
The message for Pharaoh was that “YHWH, the God of the Hebrews,” had sent Moses to him to request that he let his people leave to serve him in the wilderness, but he had not obeyed. Therefore, YHWH purposed to have the Nile struck “with the rod” so that the water would be turned into blood. The river would become toxic, causing the fish to die. It would become fowl smelling, and the Egyptians would not be able to drink the water. This would make it clear to Pharaoh that the God who had sent Moses was YHWH and needed to be obeyed. (7:16-18)
YHWH instructed Moses to tell Aaron to take his rod and stretch out his hand, apparently the arm of the hand that held the rod, over the water of Egypt. This is probably to be understood concerning the section of the Nile where they were standing and over the canals, ponds, and pools of water. All visible water would become blood, including that in wooden and stone vessels. Before the “eyes” or in the sight of Pharaoh and his servants or court officials, Aaron did as he was directed, and the water changed into blood. This was not human blood nor that of any specific animal, but the water came to look exactly like blood and came to have toxic properties. Fish were killed, and the Egyptians could not drink the water. (7:19-21) The way the water then looked may have resembled a satellite image of the Nile River that was taken in 2016. Infrared technology revealed the water to have taken on a deep red color which had resulted from the heat of the surrounding vegetation.
With their secret arts, the magicians of Egypt were able to change water into blood. The Exodus account does not say where they obtained the water. According to verse 24, the Egyptians could obtain drinking water by digging for it along the banks of the Nile. So there is a possibility that this was the source for the water the magicians used. Targum Jonathan indicates that the waters of Goshen were not affected by the miracle and says that the magicians changed these waters into blood. Subsequently Pharaoh’s heart was hardened or he became stubbornly and defiantly resistant to heeding YHWH’s word directed to him through Moses and Aaron. Pharaoh returned to his own house and gave no consideration to the miracle he had witnessed after Aaron stretched out his rod. Meanwhile, the Egyptians had to continue digging for drinking water by the Nile, for the plague lasted seven days. (7:22-25; see the Notes section.)
According to Josephus, Pharaoh derided Moses, claiming that he had run away from Egyptian slavery and returned “with deceitful tricks, wonders and magical arts to astonish him.” Moses was undaunted by what the men he whom Pharaoh summoned did with their rods. He is quoted as telling Pharaoh: “‘I do not myself despise the wisdom of the Egyptians, but I say that what I do is so much superior to what these do by magic arts and tricks, as divine power exceeds the power of man. I will demonstrate that what I do is not done by craft, or counterfeiting what is not really true, but that [the wonders] appear by the providence and power of God.’ When he had said this, he cast his rod down upon the ground and commanded it to turn itself into a serpent. It obeyed him, went all around, and devoured the rods of the Egyptians, which seemed to be dragons, until it had consumed them all. It then returned to its own form, and Moses took it into his hand again.” (Antiquities, II, xiii, 3)
Targum Jonathan names two magicians Janis and Jamberes (Jannes and Jambres). In his second letter to Timothy (3:8), the apostle Paul also referred to Jannes and Jambres as resisting Moses.
The changing of the water of the Nile River into blood (7:19-25) would have revealed the impotence of the Nile god Hapi, a fertility deity that was regarded as responsible for the Nile floods that supplied the needed water for irrigation. As Exodus 12:12 indicates, the judgments were also directed against “all the gods of Egypt.”
Regarding the effect from the plague on the water of the Nile, Josephus wrote: “The water was not only of the color of blood, but it brought upon those who ventured to drink of it great pains and bitter torment.” (Antiquities, II, xiv, 1)