Sunan Abi Dawud, Hadith 4667

Explaining the verse, “say ; You have no faith, but you only say : We have submitted our wills to Allah”, Al-Zuhri said : We think that ISLAM is a word, and faith is an action.

حَدَّثَنَا مُحَمَّدُ بْنُ عُبَيْدٍ، حَدَّثَنَا ابْنُ ثَوْرٍ، عَنْ مَعْمَرٍ، قَالَ وَقَالَ الزُّهْرِيُّ ‏{‏ قُلْ لَمْ تُؤْمِنُوا وَلَكِنْ قُولُوا أَسْلَمْنَا ‏}‏ قَالَ نَرَى أَنَّ الإِسْلاَمَ الْكَلِمَةُ وَالإِيمَانَ الْعَمَلُ ‏.‏

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also referenced under: Hadith 4684 (DarusSalam)