Musnad Ahmad 658:18

Muhammad ibn Ja'far narrated to us, Shu'bah narrated to us, from Abu Ishaq, that he heard al-Bara' saying regarding this verse: "Those of the believers who sit [at home] are not equal" [An-Nisa: 95] "to those who strive in the cause of Allah" [An-Nisa: 95]. He said: "The Messenger of Allah, peace and blessings of Allah be upon him, called for Zayd, so he brought a shoulder blade, and he wrote it down." He said: "Then Ibn Umm Maktum complained to him about his blindness, so it was revealed: 'Those of the believers who sit [at home], except those who have a disability' [An-Nisa: 95]."