It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: Every human being has a share in adultery. Thus, the eyes also commit adultery, and their adultery is looking; the hands also commit adultery, and their adultery is touching; the feet also commit adultery, and their adultery is walking (towards it); the mouth also commits adultery, and its adultery is kissing. The heart desires and wishes, and the private part either confirms or denies it.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 10920