“Give thanks unto God for His grace, but for thyself alone confess thy fault.”
The sentence separates gratitude from self-congratulation: what is received as grace is answered with thanks, while personal failure remains something to examine rather than disguise with spiritual pride.
Source details
The Imitation of Christ, Book II, Chapter X, “Of gratitude for the Grace of God,” William Benham translation, Project Gutenberg #1653. The sentence appears in the third paragraph, distinguishing thanks for grace from confession of one’s own fault within the work’s Christian theology of grace and humility.