It was mentioned in the presence of `Aisha that the Prophet (ﷺ) had appointed `Ali as successor by will. Thereupon she said, "Who said so? I saw the Prophet, while I was supporting him against my chest. He asked for a tray, and then fell on one side and expired, and I did not feel it. So how (do the people say) he appointed `Ali as his successor?"
Sahih al-Bukhari Book 64, Hadith 475
← Previous Hadith We poured medicine in one side of the Prophet's mouth during his illness and he started pointing to us, meaning to say, "Don't pour medicine in my mouth." We said, "(He says so) because a patient dislikes medicines." When he improved and felt a little better, he said, "Didn't I forbid you to pour medicine in my mouth ?" We said, " ( We thought it was because of) the dislike, patients have for medicines. He said, "Let everyone present in the house be given medicine by pouring it in his mouth while I am looking at him, except `Abbas as he has not witnessed you (doing the same to me).

Sahih al-Bukhari Book 64, Hadith 474 Next Hadith → I asked `Abdullah bin Abu `Aufa "Did the Prophet (ﷺ) make a will? ' He replied, "No." I further asked, "How comes it that the making of a will was enjoined on the people or that they were ordered to make it? " He said, "The Prophet (ﷺ) made a will concerning Allah's Book."

Sahih al-Bukhari Book 64, Hadith 476