Sahih Muslim Book 39, Hadith Number 6726.
Chapter : The splitting up of the Moon (a great miracle).
‘Abdullah b. Mas’ud reported that the moon was split up in two parts during the lifetime of Allah’s Messenger (may peace be upon him). The mountain covered one of its parts and one part of it was above the mountain and Allah’s Messenger (may peace be upon him) said: Bear witness to this.