ENOfficial
Anas said that when the people of Mecca asked God's messenger to show them a sign, he showed them the moon in two pieces between which they were able to see Hira. (Bukhari and Muslim.)
Source: sunnah.com
Other translations
Arabic
وَعَن أنسٍ قَالَ: إِنَّ أَهْلَ مَكَّةَ سَأَلُوا رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ أَنْ يُرِيَهُمْ آيَةً فَأَرَاهُمُ الْقَمَرَ شِقَّتَيْنِ حَتَّى رَأَوْا حِرَاءً بَيْنَهُمَا. مُتَّفق عَلَيْهِ
sunnah.com