The Prophet ﷺ said, "Every son of Adam has been allotted his share of fornication, which he will inevitably encounter. The fornication of the eyes is looking, the fornication of the ears is listening, the fornication of the tongue is speech, the fornication of the hands is grasping, and the fornication of the feet is walking. The heart desires and longs, and the private parts either confirm all of that or deny it."
عن النبي ﷺ قال: كتب على ابن آدم نصيبه من الزنا، مدرك ذلك لا محالة، فالعينان زناهما النظر، والأذنان زناهما الاستماع، واللسان زناه الكلام، واليد زناهما البطش، والرجل زناها الخطا، والقلب يهوى ويتمنى، ويصدق ذلك الفرج ويكذبه.
Muslim narrated it in Qadr (21:2657) from Ishaq bin Mansur, [who said] Abu Hisham Makhzumi informed us, [who said] Wahib narrated to us, [who said] Suhayl bin Abu Salih narrated to us, from his father, from Abu Hurairah, and he related it.Abu Dawud narrated it (2152) through another route from Hammad, from Suhayl bin Abu Salih, with his chain, and he added in it, "and the mouth commits zina, and its zina is kissing," and its chain is hasan.