Heidelberg Catechism Lord's Day 24

Although good works which proceed from faith do not  merit anything in the sight of God, yet God has graciously promised to reward them. This doctrine does  not make men careless, but rather careful.  (Q. 62–64.) Question 62 Q. But why cannot our good works be the whole or part of our righteousness before God?                     A. Because the righteousness which can stand before the judgment seat of God, must be perfect throughout and entirely conformable to the divine law, but even our best works in this life are all imperfect and defiled with sin. Question 63 Q. Do our good works merit nothing, even though it is God’s will to reward them in this life and in that which is to come?                      A. The reward comes not of merit, but of grace. Question 64 Q. But does not this doctrine make men careless and profane?                      A. No, for it is impossible that those who are implanted into Christ by true faith, should not bring forth fruits of thankfulness.