Sahih Muslim
The Book Giving Description of the Day of Judgement, Paradise and Hell (Kitab Sifat Al-Qiyamah wal Janna wan-Nar)
Book Number: 039 / Hadith Number: 6725
This hadith has been transmitted on the authority of Abdullah b. Mas'ud (who said): We were along with Allah's Messenger (may peace be upon him) at Mina, that moon was split up into two. One of its parts was behind the mountain and the other one was on this side of the mountain. Allah's Messenger (may peace be upbn him) said to us: Bear witness to this.