Then the LORD said to Moses, "Stretch out your hand toward heaven, that there may be darkness over the land of Egypt, a darkness to be felt." So Moses stretched out his hand toward heaven, and there was pitch darkness in all the land of Egypt three days. They did not see one another, nor did anyone rise from his place for three days, but all the people of Israel had light where they lived. Then Pharaoh called Moses and said, "Go, serve the LORD; your little ones also may go with you; only let your flocks and your herds remain behind." But Moses said, "You must also let us have sacrifices and burnt offerings, that we may sacrifice to the LORD our God. Our livestock also must go with us; not a hoof shall be left behind, for we must take of them to serve the LORD our God, and we do not know with what we must serve the LORD until we arrive there." But the LORD hardened Pharaoh's heart, and he would not let them go. Then Pharaoh said to him, "Get away from me; take care never to see my face again, for on the day you see my face you shall die." Moses said, "As you say! I will not see your face again."
Exodus 10:21-29
The final plague, leading up to the judgment upon the firstborn of Egypt, was a great, awesome darkness that came upon the land. There is surely a deep symbolical significance in this. It was the light of mercy going out for Pharaoh, did he but know it, and his reaction to it, first in seeking a further compromise (24) which was refused categorically by Moses, then in blind rage and fury dismissing the man of God with dire threats, amply confirms this, and brings the long and dramatic conflict to its climax and the beginning of its denouement. We wonder at the temerity of Pharaoh in thus threatening a man who had wielded in his presence such supernatural power (28). What did he think he could do to one who had brought these disastrous wonders upon his kingdom? But one of the penalties of closing your eyes to the obvious is that you finally become incapable of seeing it even if at last you want to. His final word to Moses serves in a fateful way to seal his own judgment (28, 29), for in excluding and banishing Moses from his presence, he excluded and banished God, Who took him at his word. This, then, is the ultimate issue of the movement that began with the words 'Who is the Lord that I should obey His voice?' (5:2). We recall an earlier word in Genesis 6:3, 'My Spirit shall not always strive with man', and see its fulfilment in Pharaoh. Nor should we lightly assume that our resistance of His will will necessarily be met by long patience and forbearance on His part. Those who try to see how far they can go in wilful disobedience without incurring divine disfavour may find too late that they have been playing with fire, and be badly and fatally burned.