(1) Afterward Moses and Aaron went and said to Pharaoh, “Thus says the Lord, the God of Israel: Let My people go that they may celebrate a festival for Me in the wilderness.”
(2) But Pharaoh said, “Who is the Lord that I should heed Him and let Israel go? I do not know the Lord, nor will I let Israel go.”
(3) They answered, “The God of the Hebrews has manifested Himself to us. Let us go, we pray, a distance of three days into the wilderness to sacrifice to the Lord our God, lest He strike us with pestilence or sword.”
(4) But the king of Egypt said to them, “Moses and Aaron, why do you distract the people from their tasks? Get to your labors!”
(1) Afterward Moses and Aaron went to Pharaoh: Earlier (3:18) the Almighty had told Moses: “Then you shall go with the elders of Israel to the king of Egypt,” but here there is no mention of the elders. The elders were apparently afraid to go to Pharaoh with Moses and Aaron, and Pharaoh therefore saw Moses and Aaron merely as lone citizens having no real constituency among the people, which immediately undermined the cogency of their arguments and demands.
And said to Pharaoh: “Thus says the Lord, the God of Israel: Let My people go that they may celebrate a festival for Me in the wilderness”: Moses and Aaron couch their demand in terms of a ritual for fulfilling a religious obligation, rather than an exigency of national-political character. But on the other hand, they do mention that the celebration is on behalf of the “God of Israel,” which nonetheless imparts to it a certain nationalist aspect.
(2) But Pharaoh said, “Who is the Lord that I should heed Him and let Israel go? I do not know the Lord, nor will I let Israel go”: When two unknowns presumptuously request an audience with Pharaoh, he does not have them arrested or summarily ejected, as we might expect, but instead asks them, “Why should I obey this God of yours, given that I have no idea who He is? If you have come with a demand, it is only right that you should justify it.” It seems that Pharaoh is being honest here – he genuinely wants to understand the Jews’ demands.
(3) They answered, “The God of the Hebrews has manifested Himself to us. Let us go, we pray, a distance of three days into the wilderness to sacrifice to the Lord our God”: Wishing to reach an understanding with Pharaoh, Moses and Aaron transition to a more understandable terminology: “The God of the ivrim, ‘Hebrews’, the descendants of Eber”. This is a more familiar concept to Pharaoh than “The Lord, the God of Israel,” as they referred to Him earlier. The ivrim are a recognized ethnic group. The “God of the Hebrews” is associated with a traditional, established religion, and should be respected. However, an appeal to Eber is still not a justification for leaving Egypt. The Jews can worship the “God of the Hebrews” right there in Egypt. There is no need for them to go out into the wilderness for that.
The Jews mission to the world operates at two distinct levels: The “national” mission, as formulated by the Patriarchs, Abraham, Isaac and Jacob (aka Israel), and the archetypal mission, as formulated by the “original Patriarchs” – Noah, Shem, and Eber. These two missions, the mission of the Children of Israel and the mission of the descendants of Eber (ivrim, Hebrews), respectively, are significantly different.
From the perspective of those “original Patriarchs,” the Jewish mission consists in the descendants and followers of Eber, the Hebrews, being scattered among the nations of the world in order to bring them the message of monotheism. Abraham’s later innovation was that his descendants (and those who joined them) would remain a separate people. The statement “Thus says the Lord, the God of Israel” is made at the national level, and it means: “We, Israel, are a foreign body with respect to Egypt.”
Israel’s religious cult is so obviously different from that of Egypt that it is impossible to properly implement it in Egypt – hence the Jews demand of Pharaoh, “Let us go, we pray, a distance of three days into the wilderness to sacrifice to the Lord our God.” Pharaoh, however, is not prepared to accept this approach, because he does not know and does not recognize the “God of Israel.”
When Moses tells Pharaoh, “Our service to God is the service of the descendants of Eber, which you cannot but know,” Pharaoh answers: “Yes, indeed, of course I know all about the service of the descendants of Eber, and I recognize it as legitimate. But that service can be performed anywhere. It does not require that you leave Egypt.”
Lest He strike us with pestilence or sword: This is a euphemistic turn of phrase, a more polite substitute for: “If you won’t allow us to go, He will surely strike you with pestilence or sword.” But even this could not bring the desired result.
(4) But the king of Egypt said to them, “Moses and Aaron, why do you distract the people from their tasks? Get to your labors!”: Since the representatives of the people did not come with you, and you came alone, this means that the people do not really want to leave Egypt. Thus, you are only distracting them from their tasks. And since this is not even an actual demand of the people, but only your own attempt to incite a rebellion, stepping up the oppression is the surest way I know to make the Jews forget about any other unreasonable demands they might have.
 For the understanding of the Ivrim, “Hebrews,” as descendants of Eber, and the role of the “Early Patriarchs” ̶ Noah, Shem, and Eber, see Bible Dynamics on Genesis, §9.3 and §12.2.
 Abraham’s importance as the progenitor of the future Jewish nation is emphasized when God first chooses him for his mission (Genesis 12:1-2). See Bible Dynamics on Genesis, §13.1.