Ben Sira 23:18

18 A man who breaks his marriage vows says to himself, "Who sees me? Darkness surrounds me, and the walls hide me, and no one sees me. Why should I fear? The Most High will not take notice of my sins."

Ben Sira 23:18 In-Context

16 Two sorts of men multiply sins, and a third incurs wrath. The soul heated like a burning fire will not be quenched until it is consumed; a man who commits fornication with his near of kin will never cease until the fire burns him up.
17 To a fornicator all bread tastes sweet; he will never cease until he dies.
18 A man who breaks his marriage vows says to himself, "Who sees me? Darkness surrounds me, and the walls hide me, and no one sees me. Why should I fear? The Most High will not take notice of my sins."
19 His fear is confined to the eyes of men, and he does not realize that the eyes of the Lord are ten thousand times brighter than the sun; they look upon all the ways of men, and perceive even the hidden places
20 Before the universe was created, it was known to him; so it was also after it was finished.
Revised Standard Version of the Bible, copyright 1952 [2nd edition, 1971] by the Division of Christian Education of the National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved.