Urwah bin al-Zubayr (may Allah have mercy on him) said: I said to Sayyidah Aishah (may Allah be pleased with her): O Mother of the Believers! I am not surprised at your knowledge of poetry, for you are the wife of the Messenger of Allah (peace and blessings be upon him) and the daughter of the most learned of people (Abu Bakr); but I am surprised at your understanding of medicine. She said: "O my nephew! When the Messenger of Allah (peace and blessings be upon him) reached the later part of his life, he fell ill, and delegations kept coming, and remedies kept being prescribed for him (peace and blessings be upon him); it was from that (that I learned medicine)."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 19599