Chasydyzm do Wyjścia 7:9

Therefore the essence of the Exodus from Egypt is at midnight, as it is written there (Exodus 11:4) "Toward midnight I will go forth among the Egyptians". For the essence of the Exodus from Egypt was through the staff of Moshe and Aaron, which are the aspect of prayer, in the aspect of judgment, the aspect of "and cast it down before Pharaoh.’ It shall turn into a serpent.” (Exodus 7:9), etc., as explained above. Therefore the essence of the Exodus from Egypt was in the middle of the night. For then, the power of prayer in the aspect of justice is aroused, as explained above. This is what our Rabbis of Blessed Memory stated (Berakhot 3b) "Did David know exactly when it was midnight? Even Moses our teacher did not know exactly when it was midnight!"..."David had a sign indicating when it was midnight. [As Rav Aḥa bar Bizna said that Rabbi Shimon Ḥasida said:] A lyre hung over David’s bed", etc. This is how it still was after the exile, and therefore they still did not know to properly determine the aspect of midnight {except for} the reverence that is evoked from the prayer. But David is Messiah, and he merits this absolutely complete prayer. For through this the complete redemption will come, and there is no exile after it. This is the aspect of (Psalms 45:4) "Gird a sword on your thigh, O mighty one", etc. "nations shall fall under you, in the heart of the king's enemies. (Psalms 45:6). And the verse (Psalms 110:2) "The staff of your might the Lord will send from Zion", etc., which is brought there in the lesson above. Regarding prayer, it is said that the essence is on David/Messiah, about whom it is said "The word of the Lord to my master; 'Wait for My right hand, until I make your enemies a footstool at your feet.'" (Psalms 110:1). For he will finish the complete redemption, because he sits at the right of Hashem Yisbarach, until He makes his enemies a footstool, etc. Therefore David obtained the time of חֲצוֹת/midnight, for he was awakened through the prayer, as seen and explained above. This is exactly what is written there, {that} David had a lyre that was hanging above his bed and when it was midnight, a northern wind blew through it and played it. This is the aspect of the wondrous melody that was explained there, which was evoked through the prayer as it is written there. Therefore, he was awakened via the northerly wind specifically, which is the aspect of strength/severities, the aspect of prayer in the aspect of judgment as seen above. That is how David knew that it was truly midnight, for the essence of the aspect of midnight, which is the aspect of the awakening from sleep, the aspect of redemption. For the exile is called sleep "in the darkness of night". And the redemption is called awakening from sleep, as it is written (Psalms 78:65) "And the Lord awoke as one asleep". All of this is evoked through the prayer in the aspect of judgment, as seen above. For this is the strength to awaken in the middle of the night, as explained above. From there, the sound of the melody is aroused, as seen above, on David's lyre through the northerly wind specifically. And therefore through this specifically he knew it was really midnight and he arouse and studied Torah, for all of this is one aspect, as explained above.

Exodus 7,9. “if Pharaoh will say to you: ‎‎‘identify yourselves by means of a miracle, say to ‎Aaron to take his staff etc.;’” at first glance ‎the word ‎לכם‎ used by Pharaoh here was superfluous as ‎Moses and Aaron did not need to identify themselves ‎to each other. He should simply have said: ‘prove your ‎mission by performing a miracle!’”
The Ari z’al writes that it is a rule that ‎every human being is convinced that his words will ‎make a favourable impression on his Creator, and as a ‎result further G’d’s dispensing of benefits to His ‎people. Because of this belief in the power of speech, ‎every person has to be extremely careful not to abuse ‎this power of speech by talking nonsense, or worse. ‎Pharaoh invited, or challenged Moses and Aaron to say ‎things which would serve as proof that due to their ‎words their G’d of whose existence Pharaoh was well ‎aware, would perform acts that would impress him. ‎When Moses therefore instructed Aaron to take his ‎staff, throw it to the ground and it would turn into a ‎snake, he complied with exactly what Pharaoh had ‎demanded of them. The miracle was the result of ‎Moses’ speaking to Aaron.‎‎