Sahih Bukhari
Merits of the Helpers in Madinah (Ansaar)
Volume: 005 / Book Number: 058 / Hadith Number: 188
Narrated 'Amr bin Maimun:
During the pre-lslamic period of ignorance I saw a she-monkey surrounded by a number of monkeys. They were all stoning it, because it had committed illegal sexual intercourse. I too, stoned it along with them.