Yahya related to me from Malik from Zayd ibn Aslam that AbuHurayra and Sad ibn Abi Waqqas used to say that someone who wasfasting was allowed to kiss. (RU)
USC-MSA web (English) reference: Book 18, Hadith 17 (RU)
Arabic reference (RU): Book 18, Hadith 650 (RU)