The revelation of the contents of the Quran to Prophet Ibrahim.

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51.24 Has there come to you information about the honored guests of Ibrahim?
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So apostles come to him,
Then

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51.31 He said: What is your affair then, O apostles!
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Prophet Ibrahim asks them why they have come. The response is....

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51.32 They said: Surely we are sent to a guilty people,
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Ok so they are talking about Prophet Lut
Until we get to.....

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51.36. But We did not find therein save a (single) house of those who submitted (the Muslims).
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This is PAST tense, like they have already been there, not that they are going there

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51.37 And We left therein a sign for those who fear the painful punishment.
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PAST tense again, they have already been there,
THEN the follow ayats (till the end of the Surah) reveal something very important...

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51.38 And in Musa: When We sent him to Firon with clear authority.
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THEN THEY TELL PROPHET IBRAHIM ABOUT PROPHET MUSA, IN PAST TENSE
So prophet Ibrahim knew about Musa. The only plausible explanation of this is that this is where the contents of the book are being revealed to Prophet Ibrahim.

I believe the Quran was written from the start, it began its documentation at Prophet Musa however and ended with Prophet Muhammad.
We just keep recycling through the pages.

For "IT IS" to occur "BE" must be set in place beforehand.

The contents of the Quran is the "BE". Before existence began the book was set.

THis can be explained from many comparative ayahs

For Example

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27.40] One who had the knowledge of the Book said: I will bring it to you in the twinkling of an eye. Then when he saw it settled beside him, he said: This is of the grace of my Lord that He may try me whether I am grateful or ungrateful; and whoever is grateful, he is grateful only for his own soul, and whoever is ungrateful, then surely my Lord is Self-sufficient, Honored.
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He knew the contents of the book and so could act accordingly.