Being free of attachments and concepts

Being free of attachments and concepts also means being free of any clinging to whatever practice you may be doing as having some intrinsic reality.
Consider the example of making offerings to the bodhisattvas.
Bodhisattvas appear in the form of spiritual friends for those who have faith, or as blessings, sacred scriptures, statues, and so on; but these manifestations are like dreams, or magical illusions, devoid of any intrinsic existence.
So indeed is everything else in the phenomenal world, so that not only the object of your offerings, but the offerings you are making, too, are all illusory.
Any result of the offering is also an illusion - which does not mean that there is no result, but the result is not a solid, concrete entity.
What sense does it make to be full of attachment and pride regarding the results of your illusory actions?
When a bodhisattva performs a beneficial action, he is totally free from clinging to the concepts of a subject who acts, an object who benefits from the action, and the action itself.
That total absence of clinging makes the merit infinite.