v1-2: The first part of the journey was part of God's plan. The route included turning back to camp; their obedience was essential in ensuring their full deliverance.
v3-4: The Egyptians would follow after the children of Israel. Pharaoh's heart was again hardened. God's power would be manifest again, and He would get glory for Himself again.
v5: The changed minds and the hardened hearts. Pharaoh and his officials realised their "mistake" in letting the children of Israel go.
v6-8: Pharaoh put together an impressive army, given the destruction that had already fallen. And he personally led the army. Again we read of his hardened heart.
v9: Pharaoh in his chariots, soon overtook the children of Israel, who were travelling by foot.
v10: The Israelites saw the Egyptians, and were afraid.
v11-12: The Israelites' response was in grumbling. This was the first of several instances of their grumbling. They had quickly forgotten God's clear promises, that He would bring them out of Egypt and into the land of the Canaanites. They had also forgotten the cruel bondage in Egypt. This attitude of grumbling persisted until the whole generation had died out in the wilderness, fulfilling their words of v11.
v13-14: In contrast to the people, Moses believed God. His only answer for the people was what God had said. He told them to stand still, rather than returning to Egypt. The people were not to be afraid, but to observe what God was going to do. The people would not have to fight. Note also that there is no mention of the goodness of the children of Israel; this is the grace of God, as He acts on behalf of His people. The defeat of the Egyptian army was to be an encouragement to the people; see v31. God had made no specific promise here to Moses, but his own faith in God was clear.
v15-18: Even Moses was rebuked for standing still. His instructions were clear. He had to raise his staff over the Red Sea, so that the waters would part for the children of Israel to cross over on dry ground. God would gain glory for Himself, as the Egyptian army pursued the Israelites into the water (v17). The testimony, that "I am the Lord" (v18). The Egyptians would know that the God of Israel was the only true God.
v19-20: At this time also, the pillar of cloud moved from in front of Israel to behind them, to prevent the Egyptians from coming any closer. The pillar meant darkness to the Egyptians, but light to the Israelites. Similarly, the Red Sea meant death to the Egyptians and life to the Israelites. The Scriptures themselves, and the testimony of Christians, are the savour of life to life and death to death; 1 Cor 1.18; 2 Cor 1.16. The Egyptians were unable to come any closer to the Israelites throughout the night.
v21-22: The waters were divided, when Moses stretched out his hand over the Sea. We read again that the Israelites went through on dry ground (as in v16), such was the power of the strong east wind that the Lord had sent. The waters are described as a wall on both sides as they walked through. Again, their walk through the waters demanded real faith; but it seems Moses led them, again demonstrating his own faith.
v23-25: The Egyptians followed the Israelites into the Sea. First the Lord sent confusion, and took off, or jammed the wheels of their chariots. The Egyptians became fearful, and tried to escape.
v26: Then Moses stretched out his hand again, to bring back the waters.
v27: The timing of Moses' action was such that the Egyptians were fleeing , and the Lord swept them into the sea.
v28: The waters covered the whole army of the Egyptians, drowning all the army.
v29: The contrast is drawn; the Israelites went through on dry ground.
v30-31: Israel had once more seen the clear evidence of God's power on their behalf. They had seen a whole catalogue of dramatic miracles. Yet few of them were full of devotion and zeal for God. Yet they did believe God. Further, Moses was magnified in their sight; compare Josh 3.7. God uses human leaders, and it is important that such are properly respected.