The Messenger of Allah ﷺ came in to visit Juwayriyah on a Friday while she was fasting.He asked her, "Did you fast yesterday?"She replied, "No."He asked, "Are you going to fast tomorrow?"She replied, "No."He said, "Then break your fast."
حدثنا وكيع حدثنا شعبة عن قتادة عن أبي أيوب الهجري
أن رسول الله ﷺ دخل على جويرية في يوم جمعة وهي صائمة فقال لها أصمت أمس قالت لا قال تصومين غدا قالت لا قال فأفطري
Its isnad is sahih. Abu Ayub Hijri is also known as Maraghi and Azdi, and he is trustworthy, his hadith is in the Sahihayn. The hadith was narrated by Bukhari 4/232 no. 1986 (Fath) and Abu Dawud 2/321 no. 2422, both in the chapter on fasting, and Abd bin Humayd 449 no. 1557.