Works of Supererogation

Voluntary works besides, over and above God's commandments — works of supererogation — cannot be taught without arrogance. For by them men declare that they not only render to God as much as they are bound to, but that they do more for His sake than of bounden duty is required. We have done only that which was our duty to do.

Even so you also, when you have done all the things that are commanded you, say, We are unworthy servants. We have done our duty.
— Luke 17:10 (WEB)

Note

Directed against the medieval Catholic doctrine of accumulated extra merit. We can never out-give God.

Bible references

Luke 17:10 · Romans 11:35-36 · Job 22:2-3 · Matthew 5:48 · 1 Corinthians 9:16 · Romans 3:23