The Messenger of Allah ﷺ said, "When night approaches, day departs, and the sun has set, the fasting person has broken his fast."
حدثنا هارون بن إسحق الهمداني حدثنا عبدة بن سليمان عن هشام بن عروة عن أبيه عن عاصم بن عمر
قال رسول الله ﷺ إذا أقبل الليل وأدبر النهار وغابت الشمس فقد أفطرت
Agreed upon by Bukhari and Muslim. Bukhari narrated it in the Book of Fasting, the chapter "When Does It Become Permissible for the Fasting Person to Break the Fast?" (no. 1954), and Muslim narrated it in the Book of Fasting, the chapter "Explaining the Time When the Fast Ends and the Day Departs" (no. 1100), from the hadith of Hisham bin Urwa, with this same wording.There are also narrations on this subject from Ibn Abu Awfa [Bukhari, no. 1941, and Muslim, no. 1101] and Abu Saeed [Bukhari, before no. 1954, as a suspended narration].