Narrated 'Aisha:
(the mother of the faithful believers) Al-Harith bin Hisham asked Allah's Messenger (ﷺ) "O Allah's Messenger! How is the Divine Inspiration revealed to you?" Allah's Messenger (ﷺ) replied, "Sometimes it is (revealed) like the ringing of a bell, this form of Inspiration is the hardest of all and then this state passes off after I have grasped what is inspired. Sometimes the Angel comes in the form of a man and talks to me and I grasp whatever he says." 'Aisha added: Verily I saw the Prophet (ﷺ) being inspired divinely on a very cold day and noticed the sweat dropping from his forehead (as the Inspiration was over).
Narrated Aisha:
Al Harith bin Hisham asked the Prophet, "How does the divine inspiration come to you?" He replied, "In all these ways: The Angel sometimes comes to me with a voice which resembles the sound of a ringing bell, and when this state abandons me, I remember what the Angel has said, and this type of Divine Inspiration is the hardest on me; and sometimes the Angel comes to me in the shape of a man and talks to me, and I understand and remember what he says."
'Ubida b. Samit reported that when wahi (inspiration) descended upon Allah's Messenger (ﷺ), he felt a burden on that account and the colour of his face underwent a change.
'A'isha reported: When revelation descended upon Allah's Messenger (ﷺ) even during the cold days, his forehead perspired.