It was narrated that Maimunah the freed (female) slave of the Messenger of Allah ﷺ, said:
“The Prophet ﷺ 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 ﷺ قَالَتْ سُئِلَ النَّبِيُّ ﷺ عَنْ رَجُلٍ قَبَّلَ امْرَأَتَهُ وَهُمَا صَائِمَانِ قَالَ " قَدْ أَفْطَرَا " .