Sahih Bukhari | Volume 9 | Hadith Number 25

Narrated by 'Aisha
We poured medicine into the mouth of the Prophet during his ailment. He said, "Don't pour medicine into my mouth." (We thought he said that) out of the aversion a patient usually has for medicines. When he improved and felt better he said, "There is none of you but will be forced to drink medicine, except Al-'Abbas, for he did not witness your deed."