Why did Allah U make an appointment with Prophet Musa u for 40 nights?
Did He not speak to him when he was on the side of the mountain of Tur? So why did Allah make an appointment with him a 2nd time in the same place that He spoke to him?
He made a 2nd appointment because in the first meeting, Allah U did not give him a Manhaj, ie a guided way. There are other surahs in which the first conversation at Tur was described with more elaboration for example in surah Taha:
﴾طه (١) مَا أَنزَلْنَا عَلَيْكَ الْقُرْآنَ لِتَشْقَىٰ (٢)﴿
“Ta, Ha. We have not sent down to you the Qur’an so that you be distressed” [Surah Taha:1-2].
And we are delighted with the Holy Qur’an by the bounty of Allah U, and never will we be distressed, and we will be delighted by its tafseer and never will we be distressed by the permission of Allah.