Musnad Abu Ya'la al-Mawsili 150:265

'Uqbah ibn Mukram narrated to us, Yunus narrated to us, Muhammad ibn Ishaq narrated to us, from Muhammad ibn Ja'far ibn al-Zubayr, from 'Urwah, from 'Aishah, who said: The sweat of the kidney—which is the flank—would seize the Messenger of Allah (may Allah bless him and grant him peace) for a month, such that he could not go out to the people. I truly saw him suffering until I would take his hand and spit into it with the Quran, then I would wipe it over his face, seeking thereby the blessing of the Quran and the blessing of his hand. I would say, "O Messenger of Allah, you are one whose supplication is answered, so supplicate to Allah to relieve you of what you are in." He would say, "O 'Aishah, I am the most severely tested of people."