أَخْبَرَنَا أَحْمَدُ بْنُ عِيسَى، قَالَ حَدَّثَنَا ابْنُ وَهْبٍ، عَنْ عَمْرٍو، عَنْ بُكَيْرٍ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ، عَنْ أَبِي هُرَيْرَةَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ ‏"‏ كُلُّ حَسَنَةٍ يَعْمَلُهَا ابْنُ آدَمَ فَلَهُ عَشْرُ أَمْثَالِهَا إِلاَّ الصِّيَامَ لِي وَأَنَا أَجْزِي بِهِ ‏"‏ ‏.‏

It was narrated from Abu Hurairah that the Prophet (PBUH) said (that Allah said): "For every good deed that the son of Adam does, he will have (the reward of) ten the like thereof, except for fasting. It is for Me and I shall reward for it. Translation Not Available

Book Ref: Sunan An Nisai Book 22 Hadith 2219
Web Ref:  Sunan An Nisai Vol 1 Book 22 Hadith 2221