Sunan Ibn Majah, Volume 2, Book 7, Hadith 1686 (DarusSalam) ⓘ
It was narrated that Maimunah the freed (female) slave of the Messenger of Allah, said: “The Prophet was asked about a man who kissed his wife when they were both fasting. He said: ‘They have broken their fast.’”
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا الْفَضْلُ بْنُ دُكَيْنٍ، عَنْ إِسْرَائِيلَ، عَنْ زَيْدِ بْنِ جُبَيْرٍ، عَنْ أَبِي يَزِيدَ الضِّنِّيِّ، عَنْ مَيْمُونَةَ، مَوْلاَةِ النَّبِيِّ ـ صلى الله عليه وسلم ـ قَالَتْ سُئِلَ النَّبِيُّ ـ صلى الله عليه وسلم ـ عَنْ رَجُلٍ قَبَّلَ امْرَأَتَهُ وَهُمَا صَائِمَانِ قَالَ " قَدْ أَفْطَرَا " .
also referenced under: Hadith 1686 (Reference) & Book 7, Hadith 1756 (In-Book)