That the Prophet ﷺ entered upon her on Friday while she was fasting. He asked: Did you fast yesterday ? She said: No. He again asked: Do you intend to fast tomorrow ? She said: No. He said: So break your fast. (Using translation from Abū Dāʾūd 2422)
أَنَّ رَسُولَ اللهِ ﷺ دَخَلَ عَلَى جُوَيْرِيَةَ بِنْتِ الْحَارِثِ يَوْمَ الْجُمُعَةِ وَهِيَ صَائِمَةٌ فَقَالَ لَهَا «أَصُمْتِ أَمْسِ؟» قَالَتْ لَا قَالَ «أَتُرِيدِينَ أَنْ تَصُومِي غَدًا؟» قَالَتْ لَا قَالَ «فَأَفْطِرِي»