The Prophet ﷺ said, "When night comes from this direction and the day departs from that direction," and Musaddad added, "and the sun has set, then the fasting person has broken his fast."
حدثنا أحمد بن حنبل حدثنا وكيع حدثنا هشام ح و حدثنا مسدد حدثنا عبد الله بن داود عن هشام المعنى قال هشام بن عروة عن أبيه
قال النبي ﷺ إذا جاء الليل من ها هنا وذهب النهار من ها هنا زاد مسدد وغابت الشمس فقد أفطر الصائم
Bukhari narrated it in the Book of Fasting, chapter "When Does It Become Permissible for the Fasting Person to Break His Fast?", hadith no. 1954, and Muslim in the Book of Fasting, chapter "Explanation of the Time When the Fast Ends and the Day Departs", hadith no. 1100, from the hadith of Hisham, through this same chain. It is also found in Musnad Ahmad, 1/28, 54.