In the exercise of charity a person avoids attributing merit to deeds, so long as he believes that all good is from the Lord.

To attribute merit to deeds executed to gain salvation is ruinous; for evils lie hidden in this of which the doer is quite unaware. Among these are denial of God's influence and working on people, trust in one's own powers in matters concerning salvation, faith in oneself and not in God, self-justification, salvation by one's own strength, the cancelling of Divine grace and mercy, the rejection of reformation and regeneration by Divine means; in particular they detract from the merit and righteousness of the Lord God the Saviour, since they claim these for themselves. Moreover they have constantly in view the reward which they regard as their first and last aim; they drown and kill love to the Lord and love towards the neighbour. They are totally ignorant of and unable to feel the pleasure of heavenly love, which is free from all idea of merit; all they feel is self-love. Putting the reward first and salvation second, so that salvation is for the sake of the reward, turns the order upside down; and such people plunge the interior desires of their minds in the self (proprium), and in the body they befoul them with the evils of the flesh. That is why in the sight of the angels good done to gain merit looks like rust, and good not done to gain merit like purple.

[2] The Lord teaches in Luke that good is not to be done to gain merit:

If you do kindnesses to those who do them to you, what credit is that to you? Rather love your enemies, and do kindnesses, and lend without expecting any return. Then your reward will be great, and you will be sons of the Most High, because He is kind to the ungrateful and wicked. Luke 6:33-36.

We learn in John that a person can do no good which is essentially good, except from the Lord:

Remain in me, and I in you. Just as the branch cannot bear fruit of itself, unless it remains part of the vine, so neither can you unless you remain in me, because without me you can do nothing. John 15:4, 5.

And elsewhere:

A man cannot take anything, unless it is given him from heaven. John 3:27.