Well, you see, in the Qu'ran, and in Islamic tradition, all of the 128 Surahs were revealed to Muhammed by the angel Gabreel (Gabriel). It was felt that Allah would not speak directly to anyone, which is in stark contract to the Jewish scriptures, in which Jehoveh-Yahweh-Hashem (take your pick) speaks directly to Moses.
Islamic tradition (this comes not from the Qu'ran but from Hadith), is that the angel Gabreel appeared to Muhammed in a cave where Muhammed often prayed and meditated. Gabreel swooped him up and squeezed the ferherkins out of him three times, commanding, "Proclaim." On the third squeeze, Muhammed uttered, trance-like, the formula, "Bismillah ir-Rahman ir-Rahim"
http://wahiduddin.net/words/bismillah.htm
which translates "In the name of Allah, the benificent, the merciful" and is the first sentence of the Qu'ran.
Now, as tradition has it, Muhammed was uncertain whether he was a genuine prophet, or simply mad. So, Muhammed went to his first wife Kadijah (and only wife at the time. For some odd reason, it was only after Kadijah's death that the other 8 wives made their appearance.) Kadijah went with Muhammed to the cave, sat on his right knee, and asked Muhammed, "Do you see the angel" and Muhammed said "yes". (By the way, I am not making this up, even though it is going to sound like some bad joke.) So Kadijah shifted to Muhammed's left knee and asked, "Now, do still see the angel" and Muhammed answered "yes." Next, Kadijah opened her clohing and exposed one breast, and said "Now, do you still see the angel?" and Muhammed said, "No, the angel went away." Kadijah, by her clever experiment, confirmed that this was a genuine angel, and not a demon, since the angel fled as the sight of the breast. Thus, Kadijah helped to convice Muhammed that he was indeed a genuine prophet, and not mad. Kadijah is considered the very first follower of Muhammed. All of Muhammed's wives are considered the mothers of all muslims, mainly because in the Qu'ran, Muhammed said so, and warned that therefore it would be monstrous for anyone to marry one of his wives after Muhammed's death.
Well, I must run and do an errand, but that is some of the story about Muhammed and the angel Gabriel.