Maliks Muwatta Book 18, Hadith Number 15.
Section : Permission for a Fasting Man to Kiss.
Yahya related to me from Malik from Yahya ibn Said that Atika bint Zayd ibn Amr ibn Nufayl, the wife of Umar ibn al-Khattab, used to kiss Umar ibn al-Khattab’s head while he was fasting, and he did not tell her not to.