ציטירנדיקער פּירוש אויף דברים 9:7

in their provocation Heb. ובהמרותם, like (Ezek. 20:8, 13, 21), “And they provoked (וימרו) me”; (Deut. 9:7), “you have been provoking (ממרים).” [This is] an expression meaning: in their provocation.

למתי אעתיר לך?, “for when shall I pray on your behalf?” Rashi comments: ”if the Torah had written מתי אעתיר, the meaning would have been: “when shall I pray?” Seeing the Torah wrote למתי, the meaning is: “concerning which time, i.e. which day shall I pray for the plague to be removed?” You find a parallel wording when Pharaoh asked for the plague of wild beasts to be removed from his land. There too the wild beasts were removed the next day (8,25-26). Although Moses prayed for the removal of the plague as soon as he left the presence of Pharaoh, the plague was not removed until the following day. The wording there confirms Rashi’s approach here.
I am surprised at the comments by Nachmanides who claims that Moses delayed praying until the following day. He claims that the letter ל in the word למתי is similar to the letter ל in the words למן היום אשר יצאת מארץ מצרים, “ever since the day you departed from the land of Egypt” (Deut. 9,7). In other words, the letter ל is integral to the word מתי, and is not a prefix. The argument of Nachmanides is that if Moses had prayed on the same day that the frogs be removed only on the morrow, then the Torah would have added the word ממחרת, “on the following day,” to its report in verse 9 that the frogs did die and would have written: “G’d did as Moses had said and the frogs died on the morrow.” Seeing that the Torah did not do so it is clear that the frogs perished immediately after Moses prayed. Seeing Pharaoh did not want them to die or retreat until the following day this leaves us with no choice but to assume that Moses held off with his prayer until the following day. Thus far Nachmanides.
I feel that if that were so the Torah would have mentioned in connection with the plague of wild beasts that Moses delayed his prayer.

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.

But they rebelled Heb. מָרוּ. They angered. Comp. (Deut. 9:7) “You were rebellious (מַמְרִים).”

in wars Heb. במהמרות, in wars and strife, an expression of (Deut. 9: 4): “You have been rebellious (ממרים).”

to provoke Heb. למרות, to provoke, as (Deut. 9:7): “you have been provoking (ממרים).”

for she has rebelled against me She has provoked Me. Comp. (Deut. 9: 24) “You have been rebellious (ממרים),” provoking.

ומורה means, one who is disobedient to the words of his father, of the same meaning as ממרים in the phrase (Deuteronomy 9:7) “ממרים הייתם”, “ye have been rebellious”.