كتاب الصيام
13  
The Book of Fasting
(12)
Chapter: Clarifying that Kissing when fasting is not unlawful for the one whose desire is not provoked by that
(12)
باب بَيَانِ أَنَّ الْقُبْلَةَ فِي الصَّوْمِ لَيْسَتْ مُحَرَّمَةً عَلَى مَنْ لَمْ تُحَرِّكْ شَهْوَتَهُ ‏‏
Sahih Muslim 1106 a

'A'isha (Allah be pleased with her) said that the Messenger of Allah (ﷺ) kissed one of his wives while he was fasting, and then she ('A'isha) smiled (as she narrated).

حَدَّثَنِي عَلِيُّ بْنُ حُجْرٍ، حَدَّثَنَا سُفْيَانُ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ عَائِشَةَ، - رضى الله عنها - قَالَتْ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم يُقَبِّلُ إِحْدَى نِسَائِهِ وَهُوَ صَائِمٌ ‏.‏ ثُمَّ تَضْحَكُ ‏.‏
Reference : Sahih Muslim 1106a
In-book reference : Book 13, Hadith 79
USC-MSA web (English) reference : Book 6, Hadith 2436
  (deprecated numbering scheme)