Rasulullah Sallallahu Alayhi Wasallam said: "adultery of the eyes is when it looks at that which is Haraam; adultery of the ears is when it listens to that which is Haraam; adultery of the tongue is when it utters Haraam; adultery of the hands is when it touches Haraam; adultery of the feet is when it walks towards Haraam; adultery of the heart is when it desires and hopes for that which is Haraam; adultery of the private parts is when it succumbs to that which is Haraam." (Targhib wa Tarhib)
From the above Hadith it is clear and apparent that Islam forbids not only the act of adultery but all acts that invite and encourage the act of Zina. Islam shuts the door to the root of every evil.
Nabi Sallallahu Alayhi Wasallam said: "There are three such people with whom Allah Ta'ala will not speak to (with words of mercy and kindness) nor will Allah Ta'ala look at them (with eyes of mercy) nor will Allah Ta'ala purify them, and for them is a painful punishment:
* An old person who commits Zina.
* A king or leader who is exceptionally deceptive (he lies a lot).
* A needy person who is proud." (Muslim)
Once Nabi Sallallahu Alayhi Wasallam remarked, "A Dayyuth [cuckold] will never enter Jannah." The Sahaba enquired, "Who is a Dayyuth?" Nabi Sallallahu Alayhi Wasallam replied, "A man who is not bothered about who visits his wife." (Sunnats)
Touching a Strange Woman with Lust – It has been reported that the person who touches a strange woman with lust, on the day of resurrection his hands will be shackled to his neck. If he kissed her, his lips will be cut off and thrown in the fire of Jahannum. If he committed adultery then his thighs will bear witness to it and testify against him on the Day of Qiyaamah. It will say to him, "I was mounted for something impermissible." Allah will look at him with anger. The flesh of his face will fall off and he will proclaim "What did I do?" His tongue will testify and say, "I spoke to whom it was not permissible for you to talk to." His legs will testify, "I walked towards something unlawful." His hands will testify "I held something which was prohibited for you." His eyes will testify "I gazed at unlawful things." His private parts will testify "I committed the act." An angel will say, "I heard it" while another will say, "I've written it down." Allah will say "I was aware of it and I concealed it." Then Allah will say to the angels "Let him taste of my punishment. My anger has increased on one who has no shame." (Kitabul-Kabaâ'ir)
In a Hadith narrated by Samurah (RA) regarding a dream of Nabi Sallallahu Alayhi Wasallam, it is mentioned that Jibraeel AS and MikAEEL AS came to Nabi Sallallahu Alayhi Wasallam.
Nabi Sallallahu Alayhi Wasallam says: "We walked until we came to something that looked like an oven. Its top section was narrow and the inside was broad. From it sounds of screaming and noise was heard."
Nabi Sallallahu Alayhi Wasallam further says: "We looked inside and we saw naked men and women. We also saw flames from beneath them. When these flames scorched them, they screamed." I asked JibraEEL (AS): "Who are these people?" He replied, "These are the males and females who committed the grave act of Zina. This will be their punishment till the day of Qiyaamah." (Bukhari)