Excerpt from 'An Enlightening Commentary into the Light of the Holy Qur'an vol. 17':
According to Tabarsi, it is also narrated from Ibn ‘Abbas that disbelievers got together one night in full moon and asked the Noble Prophet (S):
'If your claim to Prophethood is true, command the moon to cleave asunder into two halves.'
The Noble Prophet (S) inquired:'If I do so, would you believe?'
They replied:'Yes.'
Then the Noble Prophet (S) invoked God Almighty to command the moon to cleave asunder into two halves. The Noble Prophet (S) summoned disbelievers and asked them to observe Cleaving of the Moon.
It is narrated from the Noble Prophet (S) on the authority of Ibn Mas‘ud that he said:
'By Allah in Whose Hand of Might rests my soul, I witnessed the Mount of Hira through the two halves of the moon when it was cleft asunder.'