Jami` at-Tirmidhi 698
جامع الترمذي#698Sahihحَدَّثَنَا هَارُونُ بْنُ إِسْحَاقَ الْهَمْدَانِيُّ، حَدَّثَنَا عَبْدَةُ بْنُ سُلَيْمَانَ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ عَاصِمِ بْنِ عُمَرَ، عَنْ عُمَرَ بْنِ الْخَطَّابِ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " إِذَا أَقْبَلَ اللَّيْلُ وَأَدْبَرَ النَّهَارُ وَغَابَتِ الشَّمْسُ فَقَدْ أَفْطَرْتَ " . قَالَ وَفِي الْبَابِ عَنِ ابْنِ أَبِي أَوْفَى وَأَبِي سَعِيدٍ . قَالَ أَبُو عِيسَى حَدِيثُ عُمَرَ حَدِيثٌ حَسَنٌ صَحِيحٌ .
Umar bin Al-Khattab narrated that:The Messenger of Allah said: "When the night advances and the day retreats, and the sun is hidden, then the fast is to be broken
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
In-book reference: 8:17