72 Virgins (Houris) in Heaven

Mohammed knew that sex would sell very well among the group of his followers who were motivated to fight battles by the promise of sex slaves and booty. By constantly emphasizing to his followers that they would get untouched virgins in Paradise, Mohammed is clearly expressing his "high" opinion of the institution of marriage and his fairness to women. Once the followers go to heaven, they can conveniently ditch their wives for the fresher and more pleasurable sexual encounters with 'Houris' (beautiful virgins). The poor wives who gave up their virginity for the pleasure of their husbands do not get anything. But wait, Allah is all merciful! He gives the wives the rare honour of watching their husbands deflower those 72 Houris (virgins) and 28 young pre-pubescent boys.
The specific Hadith in which the number of virgins is specified is Hadith Al-Tirmidhi in the Book of Sunah (volume IV, chapters on The Features of Paradise as described by the Messenger of Allah, chapter 21, About the Smallest Reward for the People of Paradise. The same hadith is also quoted by Ibn Kathir in his Quranic commentary (Tafsir) of Surah Al-Rahman:
"The Prophet Muhammad was heard saying: 'The smallest reward for the people of paradise is an abode where there are 80,000 servants and 72 wives, over which stands a dome decorated with pearls, aquamarine, and ruby, as wide as the distance from Al-Jabiyah [a Damascus suburb] to Sana'a [Yemen]."
(QURAN 37:40-4 : "In the Gardens of Paradise, Facing one another on thrones, Round them will be passed a cup of pure wine; White, delicious to the drinkers, Neither they will have any kind of hurt, abdominal pain, headache, or sin, nor will they suffer intoxication from it. And with them will be chaste females, restraining their glances, with wide and beautiful eyes."
(QURAN 44:51-55): "Verily! The righteous will be in Paradise. Among Gardens and Springs; Dressed in fine silk and also in thick silk, facing each other, and We shall marry them to Houris with wide, lovely eyes."
(QURAN 52: 17-20): "Verily, for those who fear Allah there will be Gardens in Paradise, filled with Delight. Enjoying in that which their Lord has bestowed on them, and the fact that their Lord saved them from the torment of the blazing Fire. The Lord will say: ‘Eat and drink with happiness because of what you used to do’. They will recline with ease on thrones arranged in ranks. And We shall marry them to Houris with wide lovely eyes."
(QURAN 55:54-59): "Reclining upon the couches lined with silk brocade, and the fruits of the Gardens will be near at hand. Then which of the Blessings of your Lord will you deny? Wherein will be those houris, restraining their glances upon their husbands, whom no man or jinn has opened their hymens with sexual intercourse before. Then which of the Blessings of your Lord will you deny? In beauty they are like rubies and coral. Then which of the Blessings of your Lord will you deny?"
(QURAN 55:70-77): "Therein gardens will be fair wives good and beautiful; Then which of the Blessings of your Lord will you deny? Houris restrained in pavilions; Then which of the Blessings of your Lord will you deny? Whom no man has opened their hymens with sexual intercourse before. Then which of the Blessings of your Lord will you deny? Reclining on green cushions and rich beautiful mattresses. Then which of the Blessings of your Lord will you deny?"
(QURAN 56:37-40): "...We created the houris and made them virgins, loving companions for those on the right hand…."
(QURAN 78:31-34): "As for the righteous, they shall surely triumph. Theirs shall be gardens and vineyards, and high-bosomed virgins for companions: a truly overflowing cup."
Two points need to be noted. First, there is no mention anywhere in the Quran of the actual number of virgins available in paradise, and second, the dark-eyed damsels are available for all Muslims, not just martyrs. It is in the Islamic Traditions that we find the 72 virgins in heaven specified: in a Hadith (Islamic Tradition) collected by Al-Tirmidhi (died 892 AD) in the Book of Sunan (volume IV, chapters on The Features of Paradise as described by the Messenger of Allah [Prophet Muhammad], chapter 21, About the Smallest Reward for the People of Paradise, (Hadith 2687). The same hadith is also quoted by Ibn Kathir (died 1373 CE ) in his Quranic commentary (Tafsir) of Surah Al-Rahman (55), verse 72: "The Prophet Muhammad was heard saying: 'The smallest reward for the people of paradise is an abode where there are 80,000 servants and 72 wives, over which stands a dome decorated with pearls, aquamarine, and ruby, as wide as the distance from Al-Jabiyyah [a Damascus suburb] to Sana'a [Yemen]'."