Bible Notes Online - Exodus 7 - ESV
Commentary

v1-2: Further instructions from the Lord God to Moses; see 4.16. Aaron was to actually speak to Pharaoh, although Moses had received the instructions from God.

v3-4: Pharaoh's stubbornness was predicted by God, see 3.19. Nevertheless, he is held accountable for his unbelief. This was part of God's own plan to declare His glory (v5), which would spread beyond Egypt (see Num 22.11; Josh 2.10). The deliverance from Egypt was to be accompanied by miraculous signs and judgements.

v5: The people of Egypt would also know that the judgments that they experienced were from God, not from their own magicians, nor of natural cause.

v6: Moses and Aaron had no option; they had to obey the word of God.

v7: For completeness, the writer tells us the ages of Moses and Aaron. We know that the mistreatment of the children of Israel had begun before Moses' birth (see ch1). Thus, they had suffered 80 years under the Egyptians.

v8-9: The first sign before Pharaoh, the changing of the staff into a snake. This was given to establish the authority of Moses and Aaron. This is not generally counted amongst the ten plagues.

v10-13: We note that the Egyptian magicians had some powers to perform miracles. Compare Matt 24.24, where the Lord Jesus Christ refers to false signs being performed by those who seek to deceive. A miracle is a wonder, and a sign. But the sign need not necessarily point us to the true God. See Deut 13.1-3, where a sign can specifically indicate the worship of a false god. The children of Israel were to meet sorcery in Canaan as well, Deut 18.14. They were not to copy those ways of religious practise.

The snake thrown down by Aaron swallowed up those thrown down by the Egyptian magicians, indicting the greater power of the true God. Pharaoh's heart grew hard. In v22, and 8.7, the Egyptian magicians managed to imitate the signs performed by Moses and Aaron. They could not copy the later signs.

v14-18: The first plague was carefully explained, with Moses going to see Pharaoh early in the morning. He said that the Lord's request still stood (v16). The Lord would make Himself known through this, and the subsequent, signs. All the water in the river Nile would turn into blood; the river was of great importance for the people of Egypt, being the major water source in a hot climate.

v19: Further, the water elsewhere in Egypt would also turn into blood; streams and ponds, (irrigation) canals; even wooden buckets and stone jars in the people's houses.

v20: The various miracles occurred as Moses and Aaron raised the staff, or stretched out their hand, over Egypt (see 8.6,16; 9.22; 10.22).

v21: The plague happened just as God had said; we can imagine, perhaps, the river water changing colour by natural means, but not the water in everyone's homes. Here is an indisputable miracle.

v22: The Egyptian magicians copied this miracle.

v23-24: As a result of the Egyptians' ability to imitate the miracle, Pharaohs' heart became hard.

v25: A gap of 7 days before Moses returned to Pharaoh. The period of the plagues is several months.