These are some indications of the truthfulness of Prophet Mohammed and that the Quran is revealed from God the Lord of the heavens and the earth:
1- A large number of the Quran revelations start by the word (Say), which means: Say to them, O Mohammed.
I made a search about the word (Say), and it was 617 ayat (about 1/10 of the Quran ayat) including the word: (Say), which means: Say to them, O Mohammed.
E.g. Quran 6: 66-67, which mean:
{And your people have disbelieved the [chastisement] h, the while truly it is inevitable i; say: I am not a guardian over you j.}
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66 h As had many nations before them unbelieved also.
66 i i.e. it will inevitably afflict them.
66 j i.e. I cannot remove or avert the chastisement from you when it comes.
http://quran-ayat.com/pret/6.htm#a6_66
quran-ayat(dot)com
1- A large number of the Quran revelations start by the word (Say), which means: Say to them, O Mohammed.
I made a search about the word (Say), and it was 617 ayat (about 1/10 of the Quran ayat) including the word: (Say), which means: Say to them, O Mohammed.
E.g. Quran 6: 66-67, which mean:
{And your people have disbelieved the [chastisement] h, the while truly it is inevitable i; say: I am not a guardian over you j.}
.................................................................
66 h As had many nations before them unbelieved also.
66 i i.e. it will inevitably afflict them.
66 j i.e. I cannot remove or avert the chastisement from you when it comes.
http://quran-ayat.com/pret/6.htm#a6_66
quran-ayat(dot)com