Muwatta Malik #666
Fasting
The Arabic includes the chain of narration (sanad) and the collector's commentary; the English translation shows the Prophet's words only.
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ يَحْيَى بْنِ سَعِيدٍ، أَنَّ عَاتِكَةَ ابْنَةَ زَيْدِ بْنِ عَمْرِو بْنِ نُفَيْلٍ، - امْرَأَةَ عُمَرَ بْنِ الْخَطَّابِ - كَانَتْ تُقَبِّلُ رَأْسَ عُمَرَ بْنِ الْخَطَّابِ وَهُوَ صَائِمٌ فَلاَ يَنْهَاهَا .
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.
About Muwatta Malik
This hadith is #666 from Muwatta Malik, in the Book of Fasting.