Hadith 506540
Chapter 18: Fasting - كتاب الصيام
وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ نَافِعٍ، أَنَّ عَبْدَ اللَّهِ بْنَ عُمَرَ، كَانَ يَنْهَى عَنِ الْقُبْلَةِ، وَالْمُبَاشَرَةِ، لِلصَّائِمِ .
Yahya related to me from Malik from Nafi that Abdullah ibn Umar used to forbid kissing and fondling for people who were fasting .
Reference Muwatta Malik 506540
USC-MSA web (English) reference : Book 18, Hadith 20