Musnad Ahmad 32:643

Husayn ibn Muhammad narrated to us, Sharik narrated to us, from Jabir, from Khaythama, from Anas ibn Malik, who said: I entered with the Prophet, may Allah bless him and grant him peace, to visit Zayd ibn Arqam while he was complaining of his eye. He said to him: "O Zayd, if your sight were as it is, how would you act?" He said: "I would be patient and seek the reward [from Allah]." He said: "If your sight were as it is, then you were patient and sought the reward, you would meet Allah having no sin."