BUKHARI 3943:
from Ibn ʿAbbās —
When the Prophet ﷺ arrived at Medina he found that the Jews observed fast on the day of 'Ashura'. They were asked the reason for the fast. They replied, "This is the day when Allah caused Moses and the children of Israel to have victory over Pharaoh, so we fast on this day as a sign of glorifying it." Messenger of Allah ﷺ said, "We are closer to Moses than you." Then he ordered that fasting on this day should be observed.
البخاري ٣٩٤٣:
عن ابن عباس —
لَمَّا قَدِمَ النَّبِيُّ ﷺ الْمَدِينَةَ وَجَدَ الْيَهُودَ يَصُومُونَ عَاشُورَاءَ فَسُئِلُوا عَنْ ذَلِكَ فَقَالُوا هَذَا الْيَوْمُ الَّذِي أَظْفَرَ اللَّهُ فِيهِ مُوسَى وَبَنِي إِسْرَائِيلَ عَلَى فِرْعَوْنَ وَنَحْنُ نَصُومُهُ تَعْظِيمًا لَهُ فَقَالَ رَسُولُ اللَّهِ ﷺ نَحْنُ أَوْلَى بِمُوسَى مِنْكُمْ ثُمَّ أَمَرَ بِصَوْمِهِ
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