This event was important because this is when Muhammed hears the angel Jibril speak to him. Jibril tells him what would become the Qur'an, which is the holy book of Islam. It speaks of the revelation in 53:4-9. It states,
"It is no less than inspiration sent down to him:
He was taught by one Mighty in Power,
Endued with Wisdom: for he appeared (in stately form);
While he was in the highest part of the horizon:
Then he approached and came closer,
And was at a distance of but two bow-lengths or (even) nearer;"