Allah, the Almighty, says,
Nor come nigh to adultery: for it is an indecent (deed) and an evil way. (Al-Isra: 32)
The Quran also states,
Those who invoke not, with Allah, any other god, Nor slay such life as Allah has made sacred, except for just cause, nor commit fornication,' -and any that does this (not only) meets punishment. (But) the chastisement on the Day of Judgment will be doubled to him, and he will dwell therein in ignominy.
Allah, the Most High, says,
The woman and the man guilty of fornication, flog each of them with a hundred stripes: Let not compassion move you in their case, in a matter prescribed by Allah, if ye believe in Allah and the Last Day: And let a party of the believers witness their punishment.” (An-Nur: 2)
The punishment mentioned in the last verse concerns only single fornicators in the world as argued by the scholars. In case of married adulterers (even if they experienced marriage before) they must be stoned until death as postulated by the Prophet (pbuh). But if they escaped the worldly punishment and died without making repentance, they will be tortured in the Hell-Fire with lashes of Fire.
In the Psalms, it is narrated that Adulterers will be hanged from their genitals in the hell-Fire, on which they will be scourged with slashes of iron. If they cry out of pain, the angels of punishment will address them, "Where was this cry inaudible before? You just used to laugh, play and did not keep the thought of Allah, nor were you shy from Him."
The following hadith was stated by the Prophet (pbuh),
"An adulterer is not a believer at the time of committing adultery.” [Bukhari and Muslim]
The Prophet (pbuh) said,
"When someone fell in adultery, faith leaves his heart and overshadows him but if he extricates himself; his faith will, be restored again.” [Abu Dawud]
It was related that the Messenger of Allah (pbuh) said,
"Whoever fornicates or drinks wine, Allah takes off his faith from him as a man takes a shirt off over his head .” [Al-Hakim]
"There are three people to whom Allah, the Most High will not talk, nor will He absolve them of sins nor look at them: an aged person guilty of adultery, a king who lies and a poor beggar who is proud.” [Muslim]
On the authority of Ibn Masud who said, "I asked the Messenger of Allah (pbuh),
"What is the most grievous sin at the sight of Allah?" He said, "To associate others with Allah whereas He created you... and to commit adultery with your neighbor's wife.”
Allah, the Almighty, said,
Those who invoke not, with Allah, any other god, nor slay such life as Allah has made sacred, except for just cause, nor commit fornication; -and any that does this (not only) meets punishment. (But) the chastisement on the Day of Judgment will be doubled to him, and he will dwell therein in ignomity.
Behold! How adultery with one's neighbor, polytheism and slaying the life of others except for just cause are associated with each other.
Once, Ibn Masud asked the Prophet (P.B.U.H) saying, "O Messenger of Allah, what is the most heinous sin? The Prophet answered, "To hold that Allah has an equal, whereas He has created you. Further he asked what is next? The Prophet (pbuh) said, "To kill child lest he feeds with you. He added, "What is next? The Prophet (pbuh) said, "To commit adultery with your neighbor's wife.”
When commenting on Allah's statement,
To it are seven gates: for each of those gates is a special) class (of sinners) assigned. (Al-Hijr: 44)
Ata said, "The most grievous and hated gate of Hell is that which is assigned for adulterers who committed such crime after they had been informed of its consequences.
Makhul Ad-Dimashqi said, "When the people of the Hell-Fire smell a stinking odor they say, 'We have never smelt an odor more stinking than that, Then, they will be told that this is the odor of the adulterers' genitals. Ibn Zayd, one of great exegesists said, "This odor hurts all the people of the Hell-Fire. Of all commandments prescribed by Allah to Moses is the following,
"Do not steal and do not fill into adultery so as not to screen My Face from you."
Behold Moses is the addressee, what about the others. It was reported that the Prophet (pbuh) said,
"Satan (Iblis) often sends his soldiers everywhere in the earth saying to them, 'Whoever diverts a Muslim I will crown him. The most skillful one in diverting people, the nearest to me. Meanwhile, a devil comes and says, "I kept tempting such and such until he divorced his wife.' Iblis says, 'You did nothing. He will marry another woman.' Another comes and says, 'I kept tempting such and such until I created a grudge between him and his brother’ Iblis says, 'You did nothing. He will reconcile with him.’ Eventually comes another devil who says, 'I kept tempting such and such until he fell in adultery.’ Iblis says, 'Great and well done. Then he makes him nearer to him and crowns him.” [As-Suyuti]
We seek Allah's refuge from the evils of Satan and his soldiers.
"Faith is like a garment with which Allah covers whomever He likes. But if he falls in adultery, this garment will be taken off and if he repents He will restore it again.” [Dailami]
"O Muslims, be aware of adultery. It entails six consequences: Three in this world and the others in the next. As for the worldly consequences, they are a pale face, short life and long poverty. The consequences in the Hereafter are: The wrath of Allah, a severe reckoning and torture in Fire.” [As-Suyuti]
"Whoever persists in drinking wine and then dies, Allah will make him drink from the river of Ghuta, a river flows the genitals of the whores.” [Ahmad]
In the Fire there will be pus flowing from the whores' genitals that which will be offered to whoever dies persisting in drinking wine.
"Next to polytheism (shirk), is the semen ejaculated by a man in an unlawful womb.” [Ibn Al-Jawzi]
"In the Hell-Fire there is a valley in which contains serpents. Each serpent is as fat as a camel's neck. When it stings the one who does not pray, it's poison boils in his abode for seventy years and then his flesh is torn out. There is also a valley called the well of Hazan (suffering) which contains serpents and scorpions. Each scorpion is as huge as a mule and has seventy spines. Each spine ends in a poisonous edge. Then, it strikes the adulterer and sprays poison in his body. The adulterer suffers from this painful poison for a thousand years. Then his flesh is torn out and pus flows from his genitals.” [Not Sourced]
"Whoever makes love with a married woman, they will suffer the torture which is supposed to afflict half of this nation in grave. Afterwards, on the Day of Judgment, Allah will give her husband, who does not know (what she does), the right to dispose her good deeds. But if he knows and does nothing, he and his wife will be deprived of Paradise as there is a statement on the door of Paradise which reads, unlawful for the pimp.” [Not Sourced]
"Whoever touches a woman, who is not lawful to him, because of lust, he will be resurrected with his hand tied to his neck on the Day of Judgment. In case of kissing, his lips will be nipped in the fire. Eventually, if he fell in adultery, his thighs will witness against him, on the Day of Judgment by saying, "I lied on an unlawful" Then, Allah looks to him out of wrath. Thus, his face's flesh falls down. If he arrogantly says, "I never did so" Then the tongue witnesses by saying, 'I produced an unlawful utterance.' The hand also says, 'I touched unlawful things.' The eyes say 'I looked to the unlawful.' The legs say: 'To the unlawful objects did I walk' Finally, the genital says, 'I applied.' As for the guardian angels, he says, 'I heard, and another says, 'I wrote' eventually, Allah says, "I knew but concealed him.”
Then, Allah says,
"O angels! Take him away to torture him. Severe is My wrath on those who are not shy from Me." This is shown in Allah's Book Exalted be He:
On the Day when their tongue, their hands, and their feet will bear witness against them as to their actions. (Nur: 24).”
The most grievous kind of adultery is incenstry with one's mother, sister, stepmother and unmarriageable relatives.
The Prophet (pbuh) said,
"Whoever falls into adultery with an unmarriageable relative, must be killed.” [Al-Hakim]
AI-Barra narrated that the Messenger of Allah (pbuh) sent his uncle to a man who made love with his step mother to kill him and divide his wealth into five parts (like the spoils of war.)
Therefore, we ask Allah the Bounteous to forgive our sins for He is the Most Bounteous, the Most Kind.
Ascribing Associates To Allah, the Most High (Shirk)
Killing A Human Being
Not Performing The Prayer
Not Paying Zakat
Breaking One's Fast During Ramadan Without An Excuse
Not Performing the Hajj when Able to
Showing Disrespect to One's Parents
Severing the Ties of One's Relatives
Accepting Usurious Gain
Wrong Consuming An Orphan's Property
Lying About The Prophet
Fleeing From The Battlefield
The Leader Who Misleads His Followers, The Tyrant And The Oppressor
Arrogance, Pride, Conceit, Vanity And Haughtiness
Bearing False Witness
Accusing A Woman Of Adultery
Misappropriating Spoils Of War, Muslim Funds Or Zakat
Highwaymen Who Menace The Road
The Engulfing Oath
Taking People's Property Through Falsehood
The Consumption of Haram
The Dishonest Judge
Women Imitating Men And Vice Versa
The Pimp and the one Who Permits His Wife to Fornicate
Marrying Solely To Return To The Previous Husband
Not Freeing Oneself Of All Traces Of Urine
Showing Off In Good Work
Learning Sacred Knowledge For The Sake Of This World, Or Concealing It
Breach of Trust
Reminding Recipients of Ones Charity To Them
Disbelieving In Destiny (qadar)
Listening To People's Private Conversations
The Talebearer Who Stirs Up Enmity Between People
Breaking Promises or Pledges
Believing Fortune Tellers And Astrologers
Wife Rebelling Against Her Husband