What does the Bible say about Abraham's righteousness?

In Romans 4, Paul illustrates that Abraham's righteousness was counted to him by faith when he believed God's promises. The key verse, Romans 4:3, states that 'Abraham believed God, and it was counted unto him for righteousness.' This shows that righteousness before God is not based on human merit or adherence to the law but on trusting in God's promises, which was true even centuries before the law was given. Abraham's belief exemplifies justification by faith, a foundational doctrine in the Reformed faith.