Why did Ibn Ishaq and Ibn Hisham not mention the incident of the splitting of the moon in the Prophetic biography, despite its significance? And why did Ibn Ishaq not narrate it from Anas ibn Malik, despite meeting him, whereas Bukhari and Muslim mentioned it decades later?

The gist of the answer:

The splitting of the moon was a great miracle granted to the Prophet Muhammad, may Allah’s prayers and peace be upon him. Muslims have unanimously agreed on its occurrence, and it is evidenced by verses from the Holy Quran and recurrently transmitted (mutawatir) hadiths. The claim that this event was not recorded in Ibn Ishaq’s biographical works does not diminish its authenticity, as Ibn Ishaq did not meet the narrators of this event. Furthermore, this event was mentioned in other sources prior to Bukhari and Muslim.