Musnad Ahmad 938:89

Sulayman ibn Dawud narrated to us, Abd al-Rahman informed us, from Abu al-Zinad, from Kharijah ibn Zayd, who said: Zayd ibn Thabit said: I was sitting beside the Prophet, may Allah bless him and grant him peace, one day when revelation came to him. He said: Tranquility (al-sakinah) overcame him, and his thigh fell upon my thigh when tranquility overcame him. Zayd said: By Allah, I have never found anything heavier than the thigh of the Messenger of Allah, may Allah bless him and grant him peace. Then it was lifted from him, and he said: "Write, O Zayd." So I took a shoulder blade, and he said: "Write: {Not equal are those of the believers who sit [at home]} [An-Nisa: 95] {and those who strive} [An-Nisa: 95]," the entire verse up to his saying: {a great reward} [An-Nisa: 95]. I wrote that on the shoulder blade. Ibn Umm Maktum stood up when he heard it, and he was a blind man. He stood up when he heard the virtue of the strivers (mujahidin) and said: O Messenger of Allah, how is it for those who cannot strive, from among those who are blind and the like? Zayd said: By Allah, he had not finished his words—or it was only when he finished his words—that tranquility overcame the Prophet, may Allah bless him and grant him peace. His thigh fell upon my thigh, and I felt from its weight just as I had felt the first time. Then it was lifted from him, and he said: "Read." So I read to him: {Not equal are those of the believers who sit [at home]} [An-Nisa: 95] {and those who strive} [An-Nisa: 95]. The Prophet, may Allah bless him and grant him peace, said: "{Except those who are disabled} [An-Nisa: 95]." So I added it. By Allah, it is as if I am looking at where I added it, near a crack that was in the shoulder blade.