Musnad Abu Ya'la al-Mawsili 152:128

And from al-A’mash, from Ibrahim, from Abu Ma’mar, from ‘Abdullah, who said: We were with the Messenger of Allah (may Allah bless him and grant him peace) in Mina, and the moon split until a part of it went behind the mountain. The Messenger of Allah (may Allah bless him and grant him peace) said: "Bear witness."