Sahih al-Bukhari 4865
Sahih al-Bukhari · Book 65: Prophetic Commentary on the Qur'an (Tafseer of the Prophet (pbuh)) · "...And the moon has been cleft asunder (the people of Makkah requested Prophet Muḥammad pbuh to show them a miracle, so he showed them the splitting of the moon). And if they see a sign, they turn away..." (V.54:1,2)
Narrated `Abdullah:
حَدَّثَنَا عَلِيٌّ ، حَدَّثَنَا سُفْيَانُ ، أَخْبَرَنَا ابْنُ أَبِي نَجِيحٍ ، عَنْ مُجَاهِدٍ ، عَنْ أَبِي مَعْمَرٍ ، عَنْ عَبْدِ اللَّهِ ، قَالَ انْشَقَّ الْقَمَرُ وَنَحْنُ مَعَ النَّبِيِّ صلى الله عليه وسلم فَصَارَ فِرْقَتَيْنِ، فَقَالَ لَنَا " اشْهَدُوا، اشْهَدُوا " .
The moon was cleft asunder while we were in the company of the Prophet, and it became two parts. The Prophet (ﷺ) said, Witness, witness (this miracle).