Mukhtasar Muslim

Sayyiduna Abu Hurairah (may Allah be pleased with him) narrates from the Noble Prophet (peace and blessings of Allah be upon him) that he said: A share of adultery is written for every human being, which he will inevitably commit. The adultery of the eyes is looking, the adultery of the ears is listening, the adultery of the tongue is speaking, the adultery of the hands is grasping (and touching), the adultery of the feet is walking (towards evil), the adultery of the heart is desire and longing, and the private parts either confirm these matters or deny them.