וַיֹּ֣אמֶר מֹשֶׁ֣ה לְפַרְעֹה֮ הִתְפָּאֵ֣ר עָלַי֒ לְמָתַ֣י ׀ אַעְתִּ֣יר לְךָ֗ וְלַעֲבָדֶ֙יךָ֙ וּֽלְעַמְּךָ֔ לְהַכְרִית֙ הַֽצֲפַרְדְּעִ֔ים מִמְּךָ֖ וּמִבָּתֶּ֑יךָ רַ֥ק בַּיְאֹ֖ר תִּשָּׁאַֽרְנָה׃
I rzekł Mojżesz do Faraona: "Rozkaż mi, na kiedy pomodlić się mam za ciebie, i za sługi twoje i za lud twój, aby wytępić żaby od ciebie i z domów twoich, aby tylko w rzece zostały."
Rashi
התפאר עלי GLORY OVER ME — Similar is, (Isaiah 10:15) “Should the axe יתפאר against him that heweth therewith” i. e. should it boast, saying “I am greater than thou”; old French vanter. Therefore התפאר means pride yourself on showing your cleverness and on asking of me a difficult matter asserting that I shall be unable to do it.
Chizkuni
!התפאר עלי למתי, אעתיר, “have this boast over me about when you will release the Children of Israel, and I will pray for the frogs to disappear immediately!”
Ramban
L’MATHAI’ (AGAINST WHAT TIME) SHALL I ENTREAT FOR THEE? Rashi commented: “If the text said mathai (when) — [not l’mathai] — shall I entreat, it would signify ‘when shall I pray?’ But now that it said l’mathai, it means ‘Today I will pray for you that the frogs be destroyed by the time which you will set for me. Say then by what day you wish that they shall be destroyed.’”
In line with the plain meaning of Scripture, the removal of the plagues took place at the time of Moses’ prayer, as it is written, And Moses cried unto the Eternal, etc., and the Eternal did according to the word of Moses132Verses 8-9. and it is not written “and the Eternal did so tomorrow.” The letter lamed in the word l’mathai is no proof that Moses prayed immediately, for the word l’mathai is equivalent to mathai, there being many verses where the lamed occurs [just for elegance of language], thus: ‘l’min’ (from) the day that thou didst go forth out of the land of Egypt;133Deuteronomy 9:7. The lamed in the word l’min is superfluous. until ‘l’minchath’ (the offering) of the evening;134Ezra 9:4. There the lamed in l’minchath is a superfluous style. the wing of the one cherub was five ‘l’amoth’ (cubits).135II Chronicles 3:11. Here the lamed in l’amoth is superfluous. There are many other such cases.
In line with the plain meaning of Scripture, the removal of the plagues took place at the time of Moses’ prayer, as it is written, And Moses cried unto the Eternal, etc., and the Eternal did according to the word of Moses132Verses 8-9. and it is not written “and the Eternal did so tomorrow.” The letter lamed in the word l’mathai is no proof that Moses prayed immediately, for the word l’mathai is equivalent to mathai, there being many verses where the lamed occurs [just for elegance of language], thus: ‘l’min’ (from) the day that thou didst go forth out of the land of Egypt;133Deuteronomy 9:7. The lamed in the word l’min is superfluous. until ‘l’minchath’ (the offering) of the evening;134Ezra 9:4. There the lamed in l’minchath is a superfluous style. the wing of the one cherub was five ‘l’amoth’ (cubits).135II Chronicles 3:11. Here the lamed in l’amoth is superfluous. There are many other such cases.