וַיֵּ֤ט אַהֲרֹן֙ אֶת־יָד֔וֹ עַ֖ל מֵימֵ֣י מִצְרָ֑יִם וַתַּ֙עַל֙ הַצְּפַרְדֵּ֔עַ וַתְּכַ֖ס אֶת־אֶ֥רֶץ מִצְרָֽיִם׃
Аарон простер руку свою на воды Египетские; и вышли лягушки, и покрыли землю Египетскую.
Rashi
ותעל הצפרדע AND THE FROGS (lit. frog) CAME UP — Really there was only one frog, but when they struck at it, it was split into many swarms. This is a Midrashic explanation of the usage of the singular noun here (cf. Sanhedrin 67b; Exodus Rabbah 10:4). But as a literal explanation one must say that the swarm of the frogs is denoted by the singular form. Similar is, (v. 14) “and there was the כנם” — the swarm of insects, in old French pedulier; i. e. a swarm of lice. So, too, here, ותעל הצפרדע means: and there came up a grenouillière (old French) i. e. a swarm of frogs.
Chizkuni
ותעל הצפרדע, “the frogs emerged from the river.” Even though the Torah uses the singular mode here, the meaning is that swarms of frogs came forth. We find something similar in Numbers 21,7 when the Torah describes the plague of snakes besetting the people as if it had been only a single snake, i.e. ויסר מעלינו את הנחש, “may He remove the snake(s) from us.”
Tze'enah Ure'enah
“The frogs came up” [8:2]. One large frog came out of the water and Aaron beat all the frogs out of that one frog.23Rashi, Exodus, 8:2. The whole land became full of frogs from that one frog. The magicians also brought up frogs from the water. Pharaoh said to Moses and Aaron. Pray to God that He should take away the frogs and I will send Israel out. Moses said: when do you need me that I should pray and for which people to remove the frogs that they should only remain in the lakes? Pharaoh said: pray today that the frogs should leave tomorrow.