The Book of Fasting
22/70. Chapter:
The fast of the Prophet
Sunan an-Nasai
أَخْبَرَنَا الْقَاسِمُ بْنُ زَكَرِيَّا، قَالَ حَدَّثَنَا عُبَيْدُ اللَّهِ، قَالَ حَدَّثَنَا يَعْقُوبُ، عَنْ جَعْفَرٍ، عَنْ سَعِيدٍ، عَنِ ابْنِ عَبَّاسٍ، قَالَ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم لاَ يُفْطِرُ أَيَّامَ الْبِيضِ فِي حَضَرٍ وَلاَ سَفَرٍ .
It was narrated that Ibn 'Abbas said: "The Messenger of Allah would not break fast on the days of Al-Bid whether he was a resident or traveling."
Reference : Sunan an-Nasa'i 2345In-book reference : Book 22, Hadith 256English translation : Vol. 3, Book 22, Hadith 2347