Sunan an-Nasa'i 2291
It was narrated that Ibn 'Abbas said:
"The Messenger of Allah traveled during Ramadan and fasted until he reached 'Usfan. Then he called for a vessel and drank during the day when the prople could see him, then he did not fast."
أَخْبَرَنَا مُحَمَّدُ بْنُ قُدَامَةَ، عَنْ جَرِيرٍ، عَنْ مَنْصُورٍ، عَنْ مُجَاهِدٍ، عَنْ طَاوُسٍ، عَنِ ابْنِ عَبَّاسٍ، قَالَ سَافَرَ رَسُولُ اللَّهِ صلى الله عليه وسلم فِي رَمَضَانَ فَصَامَ حَتَّى بَلَغَ عُسْفَانَ ثُمَّ دَعَا بِإِنَاءٍ فَشَرِبَ نَهَارًا يَرَاهُ النَّاسُ ثُمَّ أَفْطَرَ ‏.‏