Heidelberg Catechism, Lord's Day 35
Lord's Day 35 of the Heidelberg Catechism addresses the believer's justification before God and the practice of prayer as a response to God's grace. This section teaches how the doctrine of justification by faith alone shapes the Christian's approach to communion with God through prayer. It provides catechetical instruction on the assurance and confidence that flows from being declared righteous in Christ.
[Lord's Day 35 text - parse manually from https://www.crcna.org/welcome/beliefs/confessions/heidelberg-catechism]