The Prophet ﷺ said, "Allah has decreed for every soul its share of fornication."
حدثنا يحيى عن ابن أبي ذئب قال حدثني خالي الحارث عن أبي سلمة
عن النبي ﷺ كتب الله على كل نفس حظها من الزنا
No references are available.
Its chain of transmission is sahih. Bukhari related it, 11/26, no. 6343, in the book of Seeking Permission, chapter on the fornication of the body parts. Muslim related it in the book of Divine Decree, chapter on the decree written for Ibn Adam of his share of fornication, 4/2046, no. 2657. And Abu Dawud related it in the book of Marriage, chapter on the command to lower the gaze, 2/246, no. 2152.