The giver of the agreeable gains the agreeable, when he gives willingly to the upright ones clothing, bedding, food, and drink, and various kinds of supplies.

Having known the Arahants to be like a field for what is relinquished and offered; not held back, the wholesome person gives what is hard to give - the giver of agreeable things gains what is agreeable.

The giver of the agreeable gains the agreeable; the giver of the foremost again gains the foremost; the giver of the excellent gains the excellent; the giver of the best reaches the best state.

The person who gives the best, the giver of the foremost, the giver of the excellent, is long-lived and famous wherever he is reborn.

(Reference: AN 5.44)

In this Teaching from Gotama Buddha, he shares how a Practitioner who gives offerings to “the upright ones” gains these benefits.

“The upright ones” are those who are practicing wholesome moral conduct.

The Buddha describes that “the wholesome person gives what is hard to give”. What he is encouraging Students to do and guiding a Practitioner to practice is, that through giving offerings of items that the mind finds it “hard to give” or difficult to give where the mind is struggling, through training the mind to practice generosity and give those items, the mind is then working to eliminate its craving/desire/attachment to those items leading to further liberation of the mind to Enlightenment.

The reason why a Practitioner might find it difficult or “hard to give” certain things is because of the mind’s craving/desire/attachment. The practice of generosity is helping the mind to “let go” so that it can be more liberated and move closer to Enlightenment.