Prophetic Commentary on the Qur'an (Tafseer of the Prophet (pbuh))
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 ".Narrated `Abdullah: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)
From Sahih al-Bukhari, whose reports the scholars accept as authentic.