Hadithcore
Sunan Abi Dawud, 4684

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 ‏.‏

References2 variants
In-Book Reference
Book 42, Hadith 89
English Reference
Book 41, Hadith 4667