I understand that in Islamic school of thought, it is said to be revelation of God's message to His chosen people like Prophets, Messengers (and according to some folks also the pious and righteous slaves of God - Ilham).
But how is it exactly delivered? Do we have any Sahih Hadiths?
From Wikipedia, I read this:
" Islamic scholars have described three ways in which God's revelation can reach His chosen individuals, especially prophets. An inspired message – not a word but an idea – can enter the heart of the chosen individuals either in the state of consciousness or in dream. The second mode, it is said, is the word heard by the person spoken to, like, from behind a veil. In the third mode, the revelation is sent from God through archangels like Gabriel and is delivered to the prophets. It is the highest form of revelation, and Muslims believe the whole Quran was revealed in this mode"
"The common mode was that Muhammad would hear sound like "the ringing of a bell" after which he found the message committed to his memory. Sometimes, the arch angel would come in human shape, most often of Dahya al-Kalbi. In two cases, Gabriel appeared in his real form. Once, on the night of Miraj, Muhammad is believed to have had a direct conversation with God. In the fifth mode, Gabriel would let the revelation enter into Muhammad’s heart."