Say:"I am no bringer of new-fangled doctrine among the messengers, nor do I know what will be done with me or with you. I follow but that which is revealed to me by inspiration: I am but a Warner open and clear."
[Qur'an 46:9]

'Ubida b. Samit(RA) reported that when wahi (inspiration) descended upon Allah's Messenger (may peace be upon him), he felt a burden on that account and the colour of his face underwent a change.