The opening exchange:
(28) Pharaoh said to him, “Be gone from me! Take care not to see me again, for the moment you look upon my face you shall die.”
(29) And Moses replied, “You have spoken rightly. I shall not see your face again!”
God addresses Moses:
(11:1) And the Lord said to Moses, “I will bring but one more plague upon Pharaoh and upon Egypt; after that he shall let you go from here; indeed, when he lets you go, he will drive you out of here one and all.
(2) Tell the people to borrow, each man from his neighbor and each woman from hers, objects of silver and gold.”
(3) The Lord disposed the Egyptians favorably toward the people. Moreover, Moses himself was much esteemed in the land of Egypt, among Pharaoh’s courtiers and among the people.
Moses further addresses Pharaoh:
(4) Moses said, “Thus says the Lord: Toward midnight I will go forth among the Egyptians,
(5) and every first-born in the land of Egypt shall die, from the first-born of Pharaoh who sits on his throne to the first-born of the slave girl who is behind the millstones; and all the first-born of the cattle.
(6) And there shall be a loud cry in all the land of Egypt, such as has never been or will ever be again;
(7) but not a dog shall snarl at any of the Israelites, at man or beast — in order that you may know that the Lord makes a distinction between Egypt and Israel.
(8) Then all these courtiers of yours shall come down to me and bow low to me, saying, ‘Depart, you and all the people who follow you!’ After that I will depart.” And he left Pharaoh’s presence in hot anger.
The end result of the first nine plagues:
(9) Now the Lord had said to Moses, “Pharaoh will not heed you, in order that My marvels may be multiplied in the land of Egypt.”
(10) Moses and Aaron had performed all these marvels before Pharaoh, but the Lord had stiffened the heart of Pharaoh so that he would not let the Israelites go from his land.
(28) Pharaoh said to him, “Be gone from me! Take care not to see me again, for the moment you look upon my face you shall die”: In the literal sense Pharaoh no longer wants to see Moses, because he is unable to withstand any additional pressure.
But there is also a different underlying meaning here. Moses’ “looking upon Pharaoh’s face,” can be understood as a reference to the assimilation of elements of Egyptian culture by the Jews, in order to carry those elements out of Egypt, and later to integrate them properly into their future civilization. The meaning of Pharaoh’s words, “for the moment you (i.e., the Jews) look upon my face you shall die” is that this process is now complete, and any further absorption of Egyptian culture by the Jews can only prove harmful to them (Jacob and his family faced an analogous situation at the end of their twenty-year stay with Laban). It is this moment that precisely determines the need for the Jews, for their own internal well-being, to leave Egypt immediately.
(29) And Moses replied, “You have spoken rightly. I shall not see your face again!”: Moses acknowledges that the Jews have already completely absorbed any and all sparks of holiness that they should take with them from Egypt. And that, furthermore, any Egyptians who wished to join Israel have already done so. Thus, there is no need for any further meetings between Israel and Egypt.
(1) And the Lord said to Moses, “I will bring but one more plague upon Pharaoh and upon Egypt; after that he shall let you go from here: Moses has not yet left Pharaoh’s presence (which happens only in v. 8), but God interrupts Moses’ conversation with Pharaoh in order to correct his position (“Indeed, when he lets you go, he will drive you out…”).
Moreover, Moses must inform Pharaoh of the impending final plague. But since Moses can never see Pharaoh again once he leaves this last meeting, he must receive the prophecy of the last plague during this same conversation with Pharaoh that is already in progress. Thus, this is the first (and only) time that Moses receives a prophecy right there in Pharaoh’s palace.
Indeed, when he lets you go, he will drive you out of here one and all: Egypt will not only allow the Jews to go, but will actually expel them. The plague of the first-born will radically alter the attitude of Egyptian society toward the Jews.
(2) Tell the people to borrow … objects of silver and gold: Although the Jews have already learned a great deal from the Egyptians, and the migration of certain elements of the Egyptian population to the Jewish side has already been completed internally, this does not mean that the release of sparks from Egypt is already complete. God stresses that the Jews must also take with them “sparks” of a different type – gold and silver – as they leave Egypt.
(3) The Lord disposed the Egyptians favorably toward the people: The transfer of a substantial portion of Egypt’s gold and silver to the Jews was not based on ordinary relations between the two peoples, but was the result of a special, ad hoc decision by the Almighty.
Moreover, Moses himself was much esteemed in the land of Egypt: Due to Moses’ authority over the forces of nature in bringing the plagues, he has achieved prominence among the Egyptians, which greatly facilitates obtaining their gold and silver. Moses’ “esteemed” position also motivated many Egyptians to join the departing Jews. On the other hand, since these people deified Moses as a personality, it was they who, during his extended absence (and assumed disappearance), demanded a replacement for him – the golden calf. And that is why God tells Moses, “Your people, whom you brought out of the land of Egypt, have acted basely” (32: 7).
The Egyptian wealth that the Jews brought out of Egypt was later subjected to “analysis and separation.” A part of the Egyptian gold was used to create the golden calf (later destroyed by being burnt and ground to powder, 32:20), while the remaining part was needed to build the Tabernacle, the “portable Temple.” This division of outcomes for the Egyptian gold likewise represents the proper Jewish attitude toward the spiritual wealth that the Jews brought with them from the Diaspora to the Land of Israel. A part of it was associated with idolatry and had to be destroyed, while the remaining part was used to build the Temple.
(4) Moses said, “Thus says the Lord”: When God is finished speaking to Moses, Moses returns to his conversation with Pharaoh, and informs him what he should expect in the near future, and how things will further develop.
Thus says the Lord: “Toward midnight I will go forth among the Egyptians”: This last plague, unlike the previous ones, is executed not by an angel, but by none other than the Almighty himself. This was the first time ever that an entire civilization en masse (i.e., Egypt) was deemed worthy of witnessing an historic Divine revelation. But because of Egypt’s depraved moral condition, this revelation became a destructive force.
(5) And every first-born in the land of Egypt shall die, from the first-born of Pharaoh who sits on his throne to the first-born of the slave girl who is behind the millstones; and all the first-born of the cattle: God had mentioned the plague of the death of the firstborns at the very beginning of His first dialogue with Moses. “I have said to you, ‘Let My son go, that he may worship Me,’ yet you refuse to let him go. Now I will slay your first-born son’ (4:23)”. This was significant, because this final plague represents not only the death of certain individuals, the firstborn of each Egyptian family, but the death of Egypt itself as the firstborn – Egypt’s fall from grace as the dominant world power. But the full extent of the impending devastation – total annihilation of all firstborns – it is only now becoming clear.
Rabbi A. I. Kook notes that Jews are here undergoing a process of liberation from the natural order, and this process happens in two stages.
The first stage is the raising of the Jewish firstborns over their Egyptian counterparts, by virtue of the plague of the death of the Egyptian firstborns, and the commandment that the Jews must redeem their firstborns (13:2,12).
The second stage is achieved when the Levites are replaced by the Jewish firstborns for performing the Temple service.
These two stages correspond to Tohorah (purification), and Kedushah (holiness), respectively. Tohorah takes place through the redemption of the firstborns, which purifies the natural order from the folly of Egyptian conceptions. And Kedushah, the transition to Jewish holiness specifically, is achieved by replacing the firstborns with the Levites (all cultures recognize the special status of firstborns, but Levites exist only among the people of Israel).
Every first-born in the land of Egypt: This does not necessarily mean that literally every firstborn died. The Torah is describing here only the “overall situation” (just as we need not understand “all the livestock of the Egyptians died” in the plague of the pestilence [9:6] to mean that all livestock perished without exception). In particular, tradition relates that although Pharaoh himself was also a firstborn, he was not affected by this tenth plague, because it was God’s plan for Pharaoh to chase down the Jews and die in the Red Sea. And among those Egyptians who had already decided to join Israel, it would seem that their firstborns too remained alive, and left Egypt with Israel the next morning.
From the first-born of Pharaoh who sits on his throne to the first-born of the slave girl who is behind the millstones; and all the first-born of the cattle: Not only Pharaoh and his entourage, but the entire Egyptian nation was guilty of oppressing the Jews. The punishment therefore falls not only on the guilty. It is a catastrophe of widespread destruction and intimidation.
(8) And he left Pharaoh’s presence in hot anger: Although the Torah does not tell us the actual reason for Moses’ anger, we could suggest the following.
Moses, an Egyptian prince in his upbringing, still has some sympathy for Egypt as the center of world civilization. At the beginning of his conversation with Pharaoh, perhaps Moses still believed that the plagues had already ended, that the Jews had by now absorbed all the “sparks” they needed to take from Egypt, and they could now leave Egypt without further ado. But now it turns out that there will be yet another plague, a plague far more severe than any that preceded it.
Although God had already informed Moses that there would be one more plague (11:1), it is possible that Moses understood that only in the general sense, and he is now shocked and even enraged when he learns of the full extent of the impending catastrophe.
But it is also possible that Moses had been hoping for further dialogue with Pharaoh, in the belief that he could still persuade Pharaoh to mend his ways. But now that Pharaoh has categorically rejected the possibility of any further dialogue, Moses understands that the situation cannot be resolved peaceably, and that catastrophic death and destruction cannot be avoided. This is why Moses leaves Pharaoh’s presence “in hot anger.”
(9) Now the Lord had said to Moses, “Pharaoh will not heed you, in order that My marvels may be multiplied in the land of Egypt”: The multitude of plagues is necessary in order to re-educate both the Egyptians and the Jews. The Ten Plagues shook the very foundations of Egyptian civilization, its self-confidence and complacency, and opened the path for humanity to receive the Divine Message.
 This happened after the incident of the golden calf.