ויתכן גם כן לפרש עד מתי יהיה זה כי ירמוז למה שכתוב (שמות ט״ו:ב׳) זה אלי ואנוהו, (שם יג) שבעבור זה עשה ה' לי, וגלה לנו הכתוב בלשון הזה על מחשבתם הרעה כי כפרו בעקר.
עד מתי יהיה זה לנו למוקש, “for how long is this one going to remain a snare for us?” According to the plain meaning of the text the servants said this on account of Moses. This explains the words זה משה האיש, “this man Moses.” (Exodus 32,1) The ערב רב had been well aware that it was Moses who had caused the plagues and that he was the Egyptians’ bane.
It is possible, however, to understand the words as aimed at the cause of the plagues, at G’d whom the Jewish people extolled in the song after the crossing of the sea (15,2) with the words זה א-לי ואנוהו, this is my G’d and I want to build God a Sanctuary.” According to this version Exodus 13 8 בעבור זה עשה ה' לי, the word זה in that verse would also be a reference to an attribute of G’d. The advisors of Pharaoh would then have revealed their true nature by still denying the supremacy of Hashem.
עד מתי יהיה זה לנו למוקש, "how long will this one continue to be a snare for us?" Pharaoh's servants were most certainly not prepared to let the Israelites depart, for the prophecy G'd had told Moses i.e. that God had hardened both the heart of Pharaoh and that of his servants would contradict such an assumption. All the servants had in mind was to ensure that the Israelites' departure would be such that they would be sure to return after having offered their sacrifices. This is why the servants did not pursue the matter once Moses had made it plain that they would take both their children and their aged with them. Their very words proved that they considered Moses' invoking G'd as the driving force behind the Israelites' demands merely as a snare. They could not believe that the great and powerful G'd whose existence Moses had demonstrated would bother to punish the Egyptians in order to let the Israelites go to the desert for three days. There is no greater denial of G'd than that.
I believe that Pharaoh's error was based on these conflicting demands by Moses on the one hand and the Israelites on the other. There could be no question that the word of G'd was the truth. Pharaoh and his servants had to consider two possibilties. 1) G'd did not desire a total departure of the Israelites but only an absence of three days' travel into the desert. 2) At the same time Pharaoh felt that the Israelites' demand for three days was a trick designed to cloak their true intentions never to return to Egypt. If so, this was proof (in the mind of Pharaoh and his servants) that the G'd of the Hebrews was unable to orchestrate an Exodus in the proper sense of the word. God had instructed God's messengers to make a lesser demand, one that God was able to perform. Keeping in mind that Pharaoh and company were non believers, they preferred an interpretation which implied that G'd's power was limited. As a result of this they remained obstinate, probing for weakness in G'd's power. When the servants contemplated the fact that they had already endured seven plagues none of which had advanced the Israelites' cause substantially, i.e. they were still enslaved in Egypt though they had not performed slave labour for a while, they had to adopt an attitude concerning the warning of the plague of locusts. The servants swung to the belief that they were not being tricked but that G'd only wanted the Israelites to leave for three days. Hence their question "how long are you going to detain these men?" They added: "send these men so that they can serve their G'd;" what they meant was that it was clear to them that all their G'd wanted was that they should serve God, not that they should leave Egypt for good. The servants attributed great destructive power to G'd and that is why they disagreed with Pharaoh's present policy. On the other hand, they were convinced that if G'd really wanted or had been able to free the Israelites completely, God would not have wasted God's time with all these plagues but would have done so at once.
(8) So Moses and Aaron were brought back to Pharaoh and he said to them, “Go, worship the LORD your God! Who are the ones to go?” (9) Moses replied, “We will all go, young and old: we will go with our sons and daughters, our flocks and herds; for we must observe the LORD’s festival.” (10) But he said to them, “The LORD be with you the same as I mean to let your children go with you! Clearly, you are bent on mischief. (11) No! You menfolk go and worship the LORD, since that is what you want.” And they were expelled from Pharaoh’s presence. (12) Then the LORD said to Moses, “Hold out your arm over the land of Egypt for the locusts, that they may come upon the land of Egypt and eat up all the grasses in the land, whatever the hail has left.” (13) So Moses held out his rod over the land of Egypt, and the LORD drove an east wind over the land all that day and all night; and when morning came, the east wind had brought the locusts. (14) Locusts invaded all the land of Egypt and settled within all the territory of Egypt in a thick mass; never before had there been so many, nor will there ever be so many again. (15) They hid all the land from view, and the land was darkened; and they ate up all the grasses of the field and all the fruit of the trees which the hail had left, so that nothing green was left, of tree or grass of the field, in all the land of Egypt. (16) Pharaoh hurriedly summoned Moses and Aaron and said, “I stand guilty before the LORD your God and before you. (17) Forgive my offense just this once, and plead with the LORD your God that God but remove this death from me.” (18) So he left Pharaoh’s presence and pleaded with the LORD. (19) The LORD caused a shift to a very strong west wind, which lifted the locusts and hurled them into the Sea of Reeds; not a single locust remained in all the territory of Egypt. (20) But the LORD stiffened Pharaoh’s heart, and he would not let the Israelites go. (21) Then the LORD said to Moses, “Hold out your arm toward the sky that there may be darkness upon the land of Egypt, a darkness that can be touched.” (22) Moses held out his arm toward the sky and thick darkness descended upon all the land of Egypt for three days. (23) People could not see one another, and for three days no one could get up from where he was; but all the Israelites enjoyed light in their dwellings. (24) Pharaoh then summoned Moses and said, “Go, worship the LORD! Only your flocks and your herds shall be left behind; even your children may go with you.” (25) But Moses said, “You yourself must provide us with sacrifices and burnt offerings to offer up to the LORD our God; (26) our own livestock, too, shall go along with us—not a hoof shall remain behind: for we must select from it for the worship of the LORD our God; and we shall not know with what we are to worship the LORD until we arrive there.” (27) But the LORD stiffened Pharaoh’s heart and he would not agree to let them go. (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!”
Pharaoh, on the other hand, was wily and had Moses and Aaron brought back to the palace to demonstrate to his servants that they were wrong, that Moses and Aaron intended to lead the whole nation out of Israel once and for all. This is why he asked Moses and Aaron who the people were that would go into the desert to offer sacrifices. When Moses and Aaron replied that everybody would be going, he accused them of bad faith (verse 10). This conversation showed Pharaoh's servants that they had been wrong in their estimate that all that was at stake was a three-day absence from work. They now reversed their previous estimate that G'd could indeed do everything God wanted, else why had Moses and Aaron not announced their true intentions at the beginning? This is the reason we do not hear the servants argue with Pharaoh anymore.