Sahih al-Bukhari 3636
Sahih al-Bukhari · Book 61: Virtues and Merits of the Prophet (pbuh) and his Companions · The miracle of the splitting of the moon
Narrated `Abdullah bin Masud:
حَدَّثَنَا صَدَقَةُ بْنُ الْفَضْلِ ، أَخْبَرَنَا ابْنُ عُيَيْنَةَ ، عَنِ ابْنِ أَبِي نَجِيحٍ ، عَنْ مُجَاهِدٍ ، عَنْ أَبِي مَعْمَرٍ ، عَنْ عَبْدِ اللَّهِ بْنِ مَسْعُودٍ ـ رضى الله عنه ـ قَالَ انْشَقَّ الْقَمَرُ عَلَى عَهْدِ رَسُولِ اللَّهِ صلى الله عليه وسلم شِقَّتَيْنِ فَقَالَ النَّبِيُّ صلى الله عليه وسلم " اشْهَدُوا " .
During the lifetime of the Prophet (ﷺ) the moon was split into two parts and on that the Prophet (ﷺ) said, "Bear witness (to thus).