-

حَدَّثَنَا عَبْدُ الرَّزَّاقِ حَدَّثَنَا مَعْمَرٌ عَنْ أَيُّوبَ عَنِ ابْنِ سَعِيدِ بْنِ جُبَيْرٍ عَنْ أَبِيهِ عَنِ ابْنِ عَبَّاسٍ قَالَ قَدِمَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ الْمَدِينَةَ فَوَجَدَ يَهُودَ يَصُومُونَ يَوْمَ عَاشُورَاءَ فَقَالَ مَا هَذَا فَقَالُوا هَذَا يَوْمٌ عَظِيمٌ يَوْمَ نَجَّى اللَّهُ مُوسَى وَأَغْرَقَ آلَ فِرْعَوْنَ فَصَامَهُ مُوسَى شُكْرًا قَالَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فَإِنِّي أَوْلَى بِمُوسَى وَأَحَقُّ بِصِيَامِهِ فَصَامَهُ وَأَمَر بِصِيَامِهِ

Narrated to us [Abdurrazaq] has told us [Ma'mar] from [Ayyub] from [Ibnu Sa'id bin Jubair] from [his father] from [Ibn Abbas] he said : The Prophet peace be upon him came to Medina, he found the Jews fasting on the day of Ashura. Then he asked: "What is this?" they answered; This is a great day, the day when Allah saved Moses and drowned Pharaoh's followers, then Musa fasted on it as a form of gratitude. The Prophet peace be upon him said: "I have more rights over Musa and have more rights over his fast." Then he fasted and ordered to fast.