Heidelberg Catechism, Lord's Day 24
Lord's Day 24 of the Heidelberg Catechism addresses the believer's gratitude and sanctification as the proper response to God's gracious justification in Christ. This catechetical material presents the foundational Reformed understanding of how the justified sinner grows in holiness and lives out covenant obedience as a grateful child of God.
[Lord's Day 24 text - parse manually from https://www.crcna.org/welcome/beliefs/confessions/heidelberg-catechism]