What is the correct explanation of the Hadith: "I saw in the pre-Islamic era (Jahiliyyah) a monkey surrounded by other monkeys that had committed adultery, so they stoned it, and I stoned it with them," and does this mean that some animals marry and commit adultery? And how can the nature and form of animal marriage to one another be explained?

The narration about the stoning of the monkeys is not from the words of the Prophet, peace be upon him, or his Companions. Rather, it is a story narrated by 'Amr ibn Maymun about what he witnessed during the pre-Islamic era (Jahiliyyah). It does not rise to the status of the Sunnah of the Prophet. Scholars have differed in its interpretation and the possibility that 'Amr ibn Maymun might have been mistaken about what occurred between the monkeys. Some have denied the applicability of the terms "fornication" (zina) and "legal punishments" (hudud) to non-accountable beings, while others have seen that the animal kingdom is full of wonders, and that what happened might be real, even if it wasn't fornication and a legal punishment in the Shari'ah sense.