The Book of Fasting
22/70. Chapter:
The fast of the Prophet
Sunan an-Nasai
أَخْبَرَنَا أَحْمَدُ بْنُ سُلَيْمَانَ، قَالَ حَدَّثَنَا زَيْدُ بْنُ الْحُبَابِ، قَالَ أَخْبَرَنِي ثَابِتُ بْنُ قَيْسٍ الْغِفَارِيُّ، قَالَ حَدَّثَنِي أَبُو سَعِيدٍ الْمَقْبُرِيُّ، قَالَ حَدَّثَنِي أَبُو هُرَيْرَةَ، عَنْ أُسَامَةَ بْنِ زَيْدٍ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم كَانَ يَسْرُدُ الصَّوْمَ فَيُقَالُ لاَ يُفْطِرُ وَيُفْطِرُ فَيُقَالُ لاَ يَصُومُ .
It was narrated from Usamah bin Zaid: That the Messenger of Allah used to fast continually and it ws said that he would not break his fast, and he used not to fast and it was said that he would not fast.
Reference : Sunan an-Nasa'i 2359In-book reference : Book 22, Hadith 270English translation : Vol. 3, Book 22, Hadith 2361