Maliks Muwatta Book 18, Hadith Number 14.
Section : Permission for a Fasting Man to Kiss.
Yahya related to me from Malik from Hisham ibn Urwa from his father that A’isha, umm al-muminin, may Allah be pleased with her, said, “The Messenger of Allah, may Allah bless him and grant him peace, used to kiss certain of his wives when fasting,” and then she laughed.