Sahih Muslim 50a

Amr al-Naqid, Abu Bakr ibn al-Nadr, and Abd ibn Humayd narrated to me—and the wording is Abd's. They said: Ya'qub ibn Ibrahim ibn Sa'd narrated to us; my father narrated to me, from Salih ibn Kaysan, from al-Harith, from Ja'far ibn Abdullah ibn al-Hakam, from Abd al-Rahman ibn al-Miswar, from Abu Rafi', from Abdullah ibn Mas'ud, that the Messenger of Allah (peace and blessings be upon him) said, ‘There was no prophet whom Allah sent to a community before me who did not have among his community disciples and companions who followed his way and took his command as an example. Then after them came successors who said what they did not do and did what they had not been commanded to do. Whoever strives against them with his hand is a believer; whoever strives against them with his tongue is a believer; and whoever strives against them with his heart is a believer. Beyond that there is not even the weight of a mustard seed of faith.’ Abu Rafi' said: I related this hadith to Abdullah ibn Umar, and he rejected it. Ibn Mas'ud then arrived and stayed at Qanat, and Abdullah ibn Umar asked me to accompany him to visit him. I went with him. When we sat down, I asked Ibn Mas'ud about this hadith, and he related it to me just as I had related it to Ibn Umar. Salih said: Something similar has also been related from Abu Rafi'.