The Heidelberg Catechism: Lord’s Day 24
62. Question: But why can our good works not be our righteousness before God, or at least a part of it?
Answer: Because the righteousness which can stand before God’s judgment must be absolutely perfect and in complete agreement with the law of God, whereas even our best works in this life are all imperfect and defiled with sin.
 Deut. 27:26; Gal. 3:10.  Is. 64:6.
63. Question: But do our good works earn nothing, even though God promises to reward them in this life and the next?
Answer: This reward is not earned; it is a gift of grace.
 Matt. 5:12; Heb. 11:6.  Luke 17:10; II Tim. 4:7, 8.
64. Question: Does this teaching not make people careless and wicked?
Answer: No. It is impossible that those grafted into Christ by true faith should not bring forth fruits of thankfulness.
 Matt. 7:18; Luke 6:43-45; John 15:5.