The Prophet ﷺ strongly committed to fast the day of Ashura

I never saw the Prophet ﷺ seeking to fast on a day that he favored more than another except this day, the day of 'Ashura', and this month, meaning the month of Ramadan.

مَا رَأَيْتُ النَّبِيَّ ﷺ يَتَحَرَّى صِيَامَ يَوْمٍ فَضَّلَهُ عَلَى غَيْرِهِ إِلاَّ هَذَا الْيَوْمَ يَوْمَ عَاشُورَاءَ وَهَذَا الشَّهْرَ يَعْنِي شَهْرَ رَمَضَانَ

he heard Ibn 'Abbas, when he was asked about the fast of 'Ashura' say: "I do not know that the Prophet fasted any day because of its virtue, except this day" meaning the month of Ramadan and the day of Ashura.'

مَا عَلِمْتُ النَّبِيَّ ﷺ صَامَ يَوْمًا يَتَحَرَّى فَضْلَهُ عَلَى الأَيَّامِ إِلاَّ هَذَا الْيَوْمَ يَعْنِي شَهْرَ رَمَضَانَ وَيَوْمَ عَاشُورَاءَ

[AI] I heard Ibn Abbas say, "I never saw the Prophet ﷺ fasting a day seeking its reward over other days except for the day of Ashura. Sufyan also said on another occasion, 'Except for this day,' referring to the day of Ashura, 'and this month,' referring to the month of Ramadan."

سَمِعْتُ ابْنَ عَبَّاسٍ يَقُولُ مَا عَلِمْتُ رَسُولَ اللهِ ﷺ صَامَ يَوْمًا يَتَحَرَّى فَضْلَهُ عَلَى الْأَيَّامِ غَيْرَ يَوْمِ عَاشُورَاءَ وَقَالَ سُفْيَانُ مَرَّةً أُخْرَى إِلا هَذَا الْيَوْمَ يَعْنِي عَاشُورَاءَ وَهَذَا الشَّهْرَ شَهْرَ رَمَضَانَ

[AI] "He heard Ibn Abbas saying, 'I did not know that the Messenger of Allah ﷺ would ever seek his virtue over others except on the day of Ashura or the month of Ramadan.'"

أَنَّهُ سَمِعَ ابْنَ عَبَّاسٍ يَقُولُ مَا عَلِمْتُ رَسُولَ اللهِ ﷺ كَانَ يَتَحَرَّىيَوْمًا يَبْتَغِي فَضْلَهُ عَلَى غَيْرِهِ إِلَّا هَذَا الْيَوْمَ يَوْمَ عَاشُورَاءَ أَوْ شَهْرَ رَمَضَانَ

he heard Ibn 'Abbas, when he was asked about the fast of 'Ashura' say: "I do not know that the Prophet fasted any day because of its virtue, except this day" meaning the month of Ramadan and the day of Ashura.' (Using translation from Nasāʾī 2370)

«مَا عَلِمْتُ النَّبِيَّ ﷺ صَامَ يَوْمًا يَتَحَرَّى فَضْلَهُ عَلَى الْأَيَّامِ إِلَّا هَذَا الْيَوْمَ يَعْنِي شَهْرَ رَمَضَانَ وَيَوْمَ عَاشُورَاءَ»