Musnad Ahmad 32:528

Yunus narrated to us, Layth narrated to us, from Yazid—meaning Ibn al-Had—from ‘Amr, from Anas ibn Malik, who said: I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: "Indeed, Allah said: 'If My servant is afflicted with his two beloved ones, then he remains patient, I will compensate him for them with Paradise.'" He meant his two eyes.