Sahih al-Bukhari 4680
Sahih al-Bukhari · Book 65: Prophetic Commentary on the Qur'an (Tafseer of the Prophet (pbuh)) · "And We took the Children of Israel across the sea, and Fir'aun (Pharaoh) and his hosts followed them in oppression and enmity, till when the drowning overtook him, he said, 'I believe that La ilaha jib (Huwa) (none has the right to be worshipped but) He (Allah), in Whom the Children of IsrAel believe, and I am one of the Muslims (those who submit to Allah's Will)." (V.10:90)
Narrated Ibn `Abbas:
حَدَّثَنِي مُحَمَّدُ بْنُ بَشَّارٍ ، حَدَّثَنَا غُنْدَرٌ ، حَدَّثَنَا شُعْبَةُ ، عَنْ أَبِي بِشْرٍ ، عَنْ سَعِيدِ بْنِ جُبَيْرٍ ، عَنِ ابْنِ عَبَّاسٍ ، قَالَ قَدِمَ النَّبِيُّ صلى الله عليه وسلم الْمَدِينَةَ وَالْيَهُودُ تَصُومُ عَاشُورَاءَ فَقَالُوا هَذَا يَوْمٌ ظَهَرَ فِيهِ مُوسَى عَلَى فِرْعَوْنَ. فَقَالَ النَّبِيُّ صلى الله عليه وسلم لأَصْحَابِهِ " أَنْتُمْ أَحَقُّ بِمُوسَى مِنْهُمْ، فَصُومُوا " .
When the Prophet (ﷺ) arrived at Medina, the Jews were observing the fast on 'Ashura' (10th of Muharram) and they said, "This is the day when Moses became victorious over Pharaoh," On that, the Prophet (ﷺ) said to his companions, "You (Muslims) have more right to celebrate Moses' victory than they have, so observe the fast on this day."