Sunan al-Nasa'i
The Book of Fasting — Hadith #2386
أَخْبَرَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، قَالَ حَدَّثَنَا أَبُو دَاوُدَ، قَالَ حَدَّثَنَا شُعْبَةُ، عَنْ قَتَادَةَ، قَالَ سَمِعْتُ مُطَرِّفَ بْنَ عَبْدِ اللَّهِ بْنِ الشِّخِّيرِ، يُحَدِّثُ عَنْ أَبِيهِ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ فِي صَوْمِ الدَّهْرِ
" لاَ صَامَ وَلاَ أَفْطَرَ " .
the Messenger of Allah said, concerning one who fasted for the rest of his life: “He neither fasted nor broke his fast.” ‘Ata said: “someone who heard him told me that Ibn ‘Umar (said) that the Prophet said: ‘Whoever fasts every day of his life, then he has not fasted.”
Chain of Narration (Isnad)