Yahya related to me from Malik from Yahya ibn Said that Atikabint Zayd ibn Amr ibn Nufayl, the wife of Umar ibn al-Khattab, used tokiss Umar ibn al-Khattab's head while he was fasting, and he did nottell her not to.
USC-MSA web (English) reference: Book 18, Hadith 15
Arabic reference: Book 18, Hadith 648