كتاب الصيام
22
The Book of Fasting
(66)
Chapter: If a person did not form the intention of fasting from the night before, can he observe a voluntary fast that day?
(66)
باب إِذَا لَمْ يُجْمِعْ مِنَ اللَّيْلِ هَلْ يَصُومُ ذَلِكَ الْيَوْمَ مِنَ التَّطَوُّعِ ‏‏
Sunan an-Nasa'i 2321
It was narrated that Yazid said:
"Salamah told us that the Messenger of Allah said to a man: 'Announce the day of Ashura. Whoever has eaten let him not eat for the rest of the day, and whoever has not eaten, let him fast."'
أَخْبَرَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، قَالَ حَدَّثَنَا يَحْيَى، عَنْ يَزِيدَ، قَالَ حَدَّثَنَا سَلَمَةُ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ لِرَجُلٍ ‏ "‏ أَذِّنْ - يَوْمَ عَاشُورَاءَ - مَنْ كَانَ أَكَلَ فَلْيُتِمَّ بَقِيَّةَ يَوْمِهِ وَمَنْ لَمْ يَكُنْ أَكَلَ فَلْيَصُمْ ‏"‏ ‏.‏
GradeSahih (Darussalam)
Reference : Sunan an-Nasa'i 2321
In-book reference : Book 22, Hadith 232
English translation : Vol. 3, Book 22, Hadith 2323