The Messenger of Allah ﷺ dictated to him the verse "Not equal are those believers who sit at home and those who strive in the cause of Allah" [Nisa 4:95]. Then Ibn Umm Maktum came while he was dictating it to me.He said, "Messenger of Allah, by Allah, if I were able to fight in jihad, I would do so." He was a blind man.Allah then sent down revelation upon His Messenger ﷺ, whose thigh was resting on my thigh. It became so heavy upon me that I feared it would crush my thigh. Then the state passed from him, and Allah revealed, "except those who are disabled" [Nisa 4:95].
أن رسول الله ﷺ أملى عليه: {لا يستوي القاعدون من المؤمنين} … {والمجاهدون في سبيل الله} فجاء ابن أم مكتوم وهو يملها علي. قال: يا رسول الله، والله لو أستطيع الجهاد لجاهدت، وكان أعمى، فأنزل الله على رسوله ﷺ، وفخذه على فخذي، فثقلت على حتى خفت أن ترض فخذي، ثم سري عنه، فأنزل الله: {غير أولي الضرر}
Bukhari narrated it in the Tafsir (4592) from Ismail bin Abdullah, who said, Ibrahim bin Saad told me, from Salih bin Kaysan, from Ibn Shihab, who said, Sahl bin Saad Saadi told me that he saw Marwan bin Hakam in the masjid, so he came forward and sat beside him. He told us that Zayd bin Thabit had informed him, and then he mentioned it.Muslim narrated it in the Imarah (1898) through another route, but did not give its wording in full, instead referring back to the hadith of Bara bin Azib that preceded it.