What is the ruling on punishing homosexuals in Islam? Is it a condition to have four witnesses to prove it? And why wasn't the ruling on stoning homosexuals mentioned in the Holy Quran?

Scholars have differed regarding the prescribed punishment for sodomy (liwat). Some believe it to be the same as the punishment for fornication/adultery (zina), while others consider it more severe, and still others less so. For the crime of sodomy to be proven, it requires either four confessions or the testimony of four upright male witnesses, just as is the case for proving zina. Many jurists considered sodomy to be sexual intercourse in a private part, encompassing both the front and back passages. As for the Quran not mentioning witnesses or stoning for sodomy, it is because the rulings concerning zina include sodomy, and the Sunnah has clarified the stoning and killing of the perpetrator of sodomy.