Sahih Muslim Book 26, Hadith Number 5486.

Chapter : Disapproval of Applying Remedy by Pouring the medicine in the mouth forcibly.

‘Aisha reported: we (intended to pour) medicine in the mouth of Allah’s Messenger (may peace be upon him) in his illness, but he pointed out (with the gesture of his hand) that it should not be poured into the mouth against his will. We said: (It was perhaps due to the natural) aversion of the patient against medicine. When he recovered, he said: Medicine should be poured into the mouth of every one of you except Ibn ‘Abbas, for he was not present amongst you.