The day of 'Ashura was one which the Jews respected and they treated it as Id. The Messenger of Allah ﷺ said: You also observe fast on this day. (Using translation from Muslim 1131a)
كَانَ يَوْمُ عَاشُورَاءَ يَوْمًا تَصُومُهُ الْيَهُودُ تَتَّخِذُهُ عِيدًا فَقَالَ رَسُولُ اللهِ ﷺ صُومُوهُ أَنْتُمْ
The day of 'Ashura' was considered as ʿId day by the Jews. So the Prophet ﷺ ordered, "I recommend you (Muslims) to fast on this day."
كَانَ يَوْمُ عَاشُورَاءَ تَعُدُّهُ الْيَهُودُ عِيدًا قَالَ النَّبِيُّ ﷺ فَصُومُوهُ أَنْتُمْ
The day of 'Ashura was one which the Jews respected and they treated it as Id. The Messenger of Allah ﷺ said: You also observe fast on this day.
كَانَ يَوْمُ عَاشُورَاءَ يَوْمًا تُعَظِّمُهُ الْيَهُودُ وَتَتَّخِذُهُ عِيدًا فَقَالَ رَسُولُ اللَّهِ ﷺ صُومُوهُ أَنْتُمْ
[Machine] The Jews used to consider the day of Ashura as a holiday, so the Messenger of Allah ﷺ said, "Oppose them, and fast on that day yourselves."
كَانَتْ يَهُودُ تَتَّخِذُ يَوْمَ عَاشُورَاءَ عِيدًا فَقَالَ رَسُولُ اللَّهِ ﷺ «خَالِفُوهُمْ صُومُوا أَنْتُمْ»
"قدْ كان عَاشورَاءُ يَوْمٌ يَصُومُه الْيَهودُ وَيَتَّخِذُونهُ عِيدًا فصُومُوه أَنْتُمْ".