Sahih Bukhari Volume 3, Book 30, Hadith 1942

حَدَّثَنَا عَلِيُّ بْنُ عَبْدِ اللَّهِ، حَدَّثَنَا سُفْيَانُ، عَنْ أَبِي إِسْحَاقَ الشَّيْبَانِيِّ، سَمِعَ ابْنَ أَبِي أَوْفَى ـ رضى الله عنه ـ قَالَ كُنَّا مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم فِي سَفَرٍ فَقَالَ لِرَجُلٍ ‏"‏ انْزِلْ فَاجْدَحْ لِي ‏"‏‏.‏ قَالَ يَا رَسُولَ اللَّهِ الشَّمْسُ‏.‏ قَالَ ‏"‏ انْزِلْ فَاجْدَحْ لِي ‏"‏‏.‏ قَالَ يَا رَسُولَ اللَّهِ الشَّمْسُ‏.‏ قَالَ ‏"‏ انْزِلْ فَاجْدَحْ لِي ‏"‏‏.‏ فَنَزَلَ، فَجَدَحَ لَهُ، فَشَرِبَ، ثُمَّ رَمَى بِيَدِهِ هَا هُنَا، ثُمَّ قَالَ ‏"‏ إِذَا رَأَيْتُمُ اللَّيْلَ أَقْبَلَ مِنْ هَا هُنَا فَقَدْ أَفْطَرَ الصَّائِمُ ‏"‏‏.‏ تَابَعَهُ جَرِيرٌ وَأَبُو بَكْرِ بْنُ عَيَّاشٍ عَنِ الشَّيْبَانِيِّ عَنِ ابْنِ أَبِي أَوْفَى قَالَ كُنْتُ مَعَ النَّبِيِّ صلى الله عليه وسلم فِي سَفَرٍ

Narrated By Ibn Abi Aufa : We were in the company of Allah's Apostle on a journey. He said to a man, "Get down and mix Sawiq (powdered barley) with water for me." The man said, "The sun (has not set yet), O Allah's Apostle." The Prophet again said to him, "Get down and mix Sawiq with water for me." The man again said, "O Allah's Apostle! The sun!" The Prophet said to him (for the third time) "Get down and mix Sawiq with water for me." The man dismounted and mixed Sawiq with water for him. The Prophet drank it and then beckoned with his hand (towards the East) and said, "When you see the night falling from this side, then a fasting person should break his fast."