Sahih al-Bukhari 4867
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 Anas:
حَدَّثَنَا عَبْدُ اللَّهِ بْنُ مُحَمَّدٍ ، حَدَّثَنَا يُونُسُ بْنُ مُحَمَّدٍ ، حَدَّثَنَا شَيْبَانُ ، عَنْ قَتَادَةَ ، عَنْ أَنَسٍ ـ رضى الله عنه ـ قَالَ سَأَلَ أَهْلُ مَكَّةَ أَنْ يُرِيَهُمْ آيَةً فَأَرَاهُمُ انْشِقَاقَ الْقَمَرِ.
The people of Mecca asked the Prophet (ﷺ) to show them a sign (miracle). So he showed them (the miracle) of the cleaving of the moon.