וַיַּ֤עַשׂ יְהוָה֙ כִּדְבַ֣ר מֹשֶׁ֔ה וַיָּ֙סַר֙ הֶעָרֹ֔ב מִפַּרְעֹ֖ה מֵעֲבָדָ֣יו וּמֵעַמּ֑וֹ לֹ֥א נִשְׁאַ֖ר אֶחָֽד׃
우리가 사흘길쯤 광야로 들어가서 우리 하나님 여호와께 희생을 드리되 우리에게 명하시는 대로 하려하나이다
Ramban
AND MOSES SAID: BEHOLD, I GO OUT FROM THEE, AND I WILL ENTREAT THE ETERNAL THAT THE SWARMS WILL DEPART FROM PHARAOH, FROM HIS SERVANTS, AND FROM HIS PEOPLE, TOMORROW.193The question here arises: Why did Moses say that he will pray that the removal of the plague be tomorrow, when Pharaoh had just said to him, Entreat for me (Verse 24)? Ramban proceeds to answer this question. Just as Pharaoh, during the plague of the frogs, had asked that it be removed tomorrow,194Above, Verse 6. so did Moses want to do it in this case as well; he would pray that the swarms [of beasts] shall depart tomorrow. And then G-d removed the swarms,195Verse 27. and they vanished completely, unlike the case of the frogs, [where Scripture states that they died].196Above, Verse 9. This was for the reason, as stated by our Rabbis,197Shemoth Rabbah 10:6. that the Holy One, blessed be He, desired to afflict them with plagues from which they would derive no benefit.198If the beasts had died in the land of Egypt, the Egyptians would have made use of their skins. Hence they just disappeared. This of course was not the case with the frogs. Now Moses guarded himself when he spoke to Pharaoh, saying to destroy the frogs,199Above, Verse 5. which alludes merely to their death, as I have explained there,199Above, Verse 5. [while here in the case of swarms, he said that the swarms will depart].
Sforno
ויעתר, in order for G’d to remove the wild beasts at the time which Pharaoh had requested and in the manner he had asked for. We know that this time Pharaoh did not want to have to contend with the stench of the dead animals as he had had to when the crocodiles died on his territory, but that G’d made all these beasts retreat to where they had been before they had invaded the urban areas of Egypt. (compare verse 27)
Tze'enah Ure'enah
“He removed the swarm of insects” [8:27]. He prayed and God removed the wild animals. Bahya asks a question. Why did the Holy One allow the wild animals to run away? Why did He not kill them, like He killed the frogs? The explanation is that He killed the frogs because they stank and made the whole land disgusting, in the expectation that this would hurt them. However, if he had killed the wild animals, then they would have had good fur skins, among them fox skins, wolf skins, and other such skins. Therefore, the Holy One allowed all the animals to run away again into the wilderness, in the expectation that they would have no benefit from them.34Bahya, Exodus, 8:27.