Sirach 23:18
Ben Sira, Ecclesiasticus17 To a fornicator all bread is sweet; he will never weary until he dies. 18 The one who sins against his marriage bed says to himself, "Who can see me? Darkness surrounds me, the walls hide me, and no one sees me. Why should I worry? The Most High will not remember sins." 19 His fear is confined to human eyes and he does not realize that the eyes of the Lord are ten thousand times brighter than the sun; they look upon every aspect of human behavior and see into hidden corners
Ambrose On the Duty of the Clergy 1.54
54 The idea of these people will not trouble us much if we look at their actions. They will not have Him to be judge over them, Whom nothing deceives; they will not grant to Him the knowledge of things hidden, for they are afraid their own hidden things may be brought to light. But the Lord, also, knowing their works, has given them over unto darkness. In the night, he says, he will be as a thief, and the eye of the adulterer will watch for the darkness, saying, No eye shall see me; he has covered up his face. For every one that avoids the light loves darkness, seeking to be hid, though he cannot be hid from God, Who knows not only what is transacted, but also what will be thought of, both in the depths of space and in the minds of men. Thus, again, he who speaks in the book Ecclesiasticus says: Who sees me? The darkness has covered me, and the walls have hidden me; whom do I fear? But although lying on his bed he may think thus, he is caught where he never thought of it. It shall be, it says, a shame to him because he knew not what the fear of the Lord was.
Notes and References
"... The Book of Ecclesiasticus [Sirach] has been honored still more highly among the Christians, being cited in the Epistle of James (Edersheim, in Wace, 'Apocrypha,' p. 21), the Didache (4:5), and the Epistle of Barnabas (19:9), while Clement of Alexandria and Origen quote from it repeatedly, as from a γραφή, or holy book. In the Western Church, Cyprian frequently appeals to it in his 'Testimonia,' as does Ambrose in the greater number of his writings. In like manner the Catalogue of Cheltenham, Damasus I., the Councils of Hippo (393) and Carthage (397), Pope Innocent I., the second Council of Carthage (419), and Augustine all regard it as a canonical book. This is contrary, however, to the opinions of the Council of Laodicea, of Jerome, and of Rufinus of Aquileia, which authorities rank it among the ecclesiastical books. It was finally declared canonical by the Council of Trent; and the favor with which the Church has always regarded it has preserved it in its entirety. ..."
Toy, Crawford Howell The Wisdom of Jesus the Son of Sirach (pp. 1-10) Jewish Encyclopedia, 2021