Musannaf Ibn Abi Shayba 3:3908

Abu Mu'awiyah narrated to us, from al-A'mash, from al-Musayyab ibn Rafi', from Ibn Abbas, who said: When his eyesight failed, a man came to him and said: "If I treat it for you, provided that you are patient with me for seven [days]—not praying except while lying on your back—I will treat you, and I hope that your eyes will be healed." Ibn Abbas sent [word] to Aisha, Abu Hurayrah, and others among the companions of Muhammad, may Allah bless him and grant him peace. He said: "All of them said: 'Have you considered if you were to die during these seven [days], how would you perform the prayer?'" He said: So he left his eyes and did not treat them.