The moon split during the time of the Prophet ﷺ into two pieces, and he said to us, "Bear witness, bear witness."
انشق القمر مع النبي ﷺ فصار فرقتين فقال لنا: أشهدوا أشهدوا
Bukhari narrated it in the tafsir chapter (4865) and Muslim in the chapter on the characteristics of the hypocrites (2800), both from the hadith of Sufyan, who said, "Ibn Abu Najeeh informed us, from Mujahid, from Abu Muamar, from Abdullah bin Masud," and he related it.In another version transmitted by both of them, he said, "While we were with the Messenger of Allah ﷺ at Mina, the moon suddenly split into two halves. One half was behind the mountain, and the other half was in front of it." The Messenger of Allah ﷺ then said, "Bear witness."In Musnad Imam Ahmad (3924), from Muammal, from Israil, from Simak, from Ibrahim, from Aswad, from Abdullah bin Masud, who said, "The moon split during the time of the Messenger of Allah ﷺ, until I saw the mountain through the gap between the two halves of the moon."Muammal is Ibn Ismail, who has a weak memory, but he has been corroborated. Hakim narrated it (2/471) from the hadith of Saeed bin Sabiq, from Israil, through the same chain, and he graded it sahih.There are other hadiths on this subject, see the book on miracles and the tafsir.