Sahih al-Bukhari 3636
Book 61: Virtues and Merits of the Prophet (pbuh) and his Companions · Narrated by `Abdullah bin Masud
Arabic
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 ".
English translation
Narrated `Abdullah bin Masud:During the lifetime of the Prophet (ﷺ) the moon was split into two parts and on that the Prophet (ﷺ) said, "Bear witness (to this)
Reference: Sahih al-Bukhari 3636, Book of Virtues and Merits of the Prophet (pbuh) and his Companions. English translation by Dr. Muhammad Muhsin Khan.