Narrated 'Aisha:

(the mother of the faithful believers) Al-Harith bin Hisham asked Allah's Messenger (ﷺ) "O Allah's Messenger (ﷺ)! 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).