Sahih al-Bukhari 5709-5712
Medicine
Al-Ladud (the medicine which is poured or inserted into one side of a patient’s mouth)
Narrated Ibn `Abbas and `Aisha: Abu Bakr kissed (the forehead of) the Prophet (ﷺ) when he was dead. `Aisha added: We put medicine in one side of his mouth but he started waving us not to insert the medicine into his mouth. We said, "He dislikes the medicine as a patient usually does." But when he came to his senses he said, "Did I not forbid you to put medicine (by force) in the side of my mouth?" We said, "We thought it was just because a patient usually dislikes medicine." He said, "None of those who are in the house but will be forced to take medicine in the side of his mouth while I am watching, except Al-`Abbas, for he had not witnessed your deed."