Sahih Muslim 1101 b
Ibn Abi Aufa (Allah be pleased with him) reported:
We were with the Messenger of Allah (ﷺ) on a journey. When the sun sank he said to a person: Get down and prepare barley meal for us. Upon this he said: Messenger of Allah, let there be dusk. (He the Holy Prophet) said: Get down and prepare barley meal for us. He (the person) said: There is still (the light of) day upon us. (But) he got down (in obedience to the command of the Holy Prophet) and prepared a barley meal for him and he (the Holy Prophet) drank that (liquid meal) and then said: When you see the night approaching from that side (west) (and he pointed towards the east with his hand), then the observer of the fast should break it.
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا عَلِيُّ بْنُ مُسْهِرٍ، وَعَبَّادُ بْنُ الْعَوَّامِ، عَنِ الشَّيْبَانِيِّ، عَنِ ابْنِ أَبِي أَوْفَى، - رضى الله عنه - قَالَ كُنَّا مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم فِي سَفَرٍ فَلَمَّا غَابَتِ الشَّمْسُ قَالَ لِرَجُلٍ ‏"‏ انْزِلْ فَاجْدَحْ لَنَا ‏"‏ ‏.‏ فَقَالَ يَا رَسُولَ اللَّهِ لَوْ أَمْسَيْتَ ‏.‏ قَالَ ‏"‏ انْزِلْ فَاجْدَحْ لَنَا ‏"‏ ‏.‏ قَالَ إِنَّ عَلَيْنَا نَهَارًا ‏.‏ فَنَزَلَ فَجَدَحَ لَهُ فَشَرِبَ ثُمَّ قَالَ ‏"‏ إِذَا رَأَيْتُمُ اللَّيْلَ قَدْ أَقْبَلَ مِنْ هَا هُنَا - وَأَشَارَ بِيَدِهِ نَحْوَ الْمَشْرِقِ - فَقَدْ أَفْطَرَ الصَّائِمُ ‏"‏ ‏.‏