(66) باب إِذَا لَمْ يُجْمِعْ مِنَ اللَّيْلِ هَلْ يَصُومُ ذَلِكَ الْيَوْمَ مِنَ التَّطَوُّعِ
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."' (ES)
Reference (ES): Sunan an-Nasa'i 2321 (ES)
In-book reference (ES): Book 22, Hadith 232 (ES)
English translation (ES): Vol. 3, Book 22, Hadith 2323 (ES)