Musnad Ahmad 938:26

'Abd al-Razzaq narrated to us, Ma'mar informed us, from al-Zuhri, from Qabisah ibn Dhu'ayb, from Zayd ibn Thabit, who said: I used to write for the Messenger of Allah, may Allah bless him and grant him peace. He said: "Write: {Not equal are those who sit} [An-Nisa: 95] {and those who strive in the way of Allah} [An-Nisa: 95]." Then 'Abdullah ibn Umm Maktum came and said: "O Messenger of Allah, I love striving in the way of Allah, but I have an infirmity, and you see my condition, and my eyesight is gone." Zayd said: Then the thigh of the Messenger of Allah, may Allah bless him and grant him peace, became heavy upon my thigh, until I feared it would crush it. Then he said: "Write: {Not equal are those who sit among the believers, other than those who have an injury, and those who strive in the way of Allah} [An-Nisa: 95]."