Sayyiduna Abu Hurairah (may Allah be pleased with him) narrated from the Messenger of Allah (peace and blessings be upon him), he said: "The adultery of the eyes is looking, the adultery of the tongue is speaking, and the adultery of the hand is touching, and the adultery of the stomach, the adultery of the feet is walking. The private part either confirms it or denies it."
Hadith Referenceمسند اسحاق بن راهويه / كتاب الايمان / 43
Hadith Takhrij«بخاري ، كتاب القدر ، رقم : 6612 . مسلم ، كتاب القدر ، باب قدر على ابن آدم حظه من الزني ، رقم : 2657»