كتاب التوحيد
Oneness, Uniqueness of Allah (Tawheed)
Chapter: What the Prophet (saws) mentioned and narrated of his Lord’s Sayings
باب ذِكْرِ النَّبِيِّ صلى الله عليه وسلم وَرِوَايَتِهِ عَنْ رَبِّهِ
Sahih al-Bukhari 7538

Narrated Abu Huraira:

The Prophet (ﷺ) said that your Lord said, "Every (sinful) deed can be expiated; and the fast is for Me, so I will give the reward for it; and the smell which comes out of the mouth of a fasting person, is better in Allah's Sight than the smell of musk." (See Hadith No. 584)

حَدَّثَنَا آدَمُ، حَدَّثَنَا شُعْبَةُ، حَدَّثَنَا مُحَمَّدُ بْنُ زِيَادٍ، قَالَ سَمِعْتُ أَبَا هُرَيْرَةَ، عَنِ النَّبِيِّ صلى الله عليه وسلم يَرْوِيهِ عَنْ رَبِّكُمْ، قَالَ ‏ "‏ لِكُلِّ عَمَلٍ كَفَّارَةٌ، وَالصَّوْمُ لِي وَأَنَا أَجْزِي بِهِ، وَلَخَلُوفُ فَمِ الصَّائِمِ أَطْيَبُ عِنْدَ اللَّهِ مِنْ رِيحِ الْمِسْكِ ‏"‏‏.‏
Reference : Sahih al-Bukhari 7538
In-book reference : Book 97, Hadith 163
USC-MSA web (English) reference : Vol. 9, Book 93, Hadith 629
  (deprecated numbering scheme)