(44) باب يُفْطِرُ بِمَا تَيَسَّرَ عَلَيْهِ بِالْمَاءِ وَغَيْرِهِ
Narrated `Abdullah bin Abi `Aufa:
We were traveling with Allah's Messenger (ﷺ) and he was fasting, and when the sun set, he said to (someone), "Get down and mix Sawiq with water for us." He replied, "O Allah's Messenger (ﷺ)! (Will you wait) till it is evening?" The Prophet (ﷺ) again said, "Get down and mix Sawiq with water for us." He replied, "O Allah's Messenger (ﷺ)! It is still daytime." The Prophet (ﷺ) said again, "Get down and mix Sawiq with water for us." So, he got down and carried out that order. The Prophet (ﷺ) then said, "When you see night falling from this side, the fasting person should break his fast," and he beckoned with his finger towards the east.
Reference: Sahih al-Bukhari 1956
In-book reference: Book 30, Hadith 63
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 3, Book 31, Hadith 177