Sahl bin Sa'd (may Allah be pleased with him) said: I entered the mosque and Marwan bin al-Hakam was sitting there, so I sat with him, and he told us that Sayyiduna Zayd bin Thabit (may Allah be pleased with him) had told him that the Messenger of Allah (peace and blessings be upon him) dictated to him this verse: "Not equal are those who sit back and those who strive" [Surah al-Nisa: 95]. At that, Ibn Umm Maktum (may Allah be pleased with him) said: By Allah! O Messenger of Allah, if I had the strength for jihad, I would certainly strive in jihad. Thereupon Allah, the Mighty and Majestic, sent down revelation upon him (peace and blessings be upon him) while his (peace and blessings be upon him) thigh was on my thigh, and his (peace and blessings be upon him) thigh became so heavy upon me that it felt as if my thigh would be crushed. Then the state of revelation lifted from him (peace and blessings be upon him), and he said: "Except those who are disabled" [Surah al-Nisa: 95].
Hadith Referenceالمعجم الكبير للطبراني / باب الزاي / 4797