Quraish polytheists, Walid b. Mughira, Abu Jahl. As b. Wail, As b. Hisham, Aswad b. Abdi Yaghus, Aswad b. Muttalib, Zama b. Aswad, Nadr b. Harith and others (11) said to the prophet Muhammad (PBUH):

“If you truly are a Prophet that has been appointed by Allah, then split the moon in half. Let it be in such a way that one half will appear over the Mount Abu Qubais and the other half will be seen over Mount Quayqian.”

The prophet Muhammad (PBUH) asked:

“If I do it, will you become Muslims?”

The polytheists answered:

“Yes, we will.”

On the 14th night, when it was full moon, the prophet Muhammad (PBUH) wanted Almighty Allah to give him the miracle which the polytheists demanded from him. (12)

When the Gabriel (AS) informed the prophet Muhammad (PBUH) that God had accepted his prayer, he announced it to the Meccans. The polytheists witnessed the splitting of the moon on the 14th night.

https://questionsonislam.com/article/miracle-splitting-moon-0