From Nagarjuna's Treatise on the Great Perfection of Wisdom
Question: Which is supreme, the giving of material wealth or the giving of Dharma?
Response: According to the words of the Buddha, among the two kinds of giving, the giving of Dharma is supreme. Why is that? The reward resulting from the giving of material wealth is experienced within the desire realm. The reward resulting from the giving of Dharma may be experienced within the three realms or beyond the three realms.
Moreover, if one's discourse is pure, if it reaches deeply into its principles, and if one's mind also realizes it, then, on that account one reaches beyond the three realms.
Again, whereas the giving of material wealth is measurable, the giving of Dharma is measureless. Material giving is such as can be exhausted. The giving of Dharma is inexhaustible. It is analogous to throwing fuel onto a fire: its brightness becomes even greater.
Then again, in the reward gained from the giving of material wealth there is less purity and more defilement. In the reward gained from the giving of Dharma, there is less defilement and more purity.
Also, if one engages in the giving of material wealth, one depends on the power of many others. The giving of Dharma comes forth from the mind. It does not depend upon others.
Additionally, the giving of material wealth is able to cause enhancement of the faculties associated with the four-element [body]. The giving of Dharma is able to bring about perfection of non-outflows in the [five] faculties, the [five] powers, the [seven limbs of] enlightenment and the [eight-fold] path.
Also, as for the methods of giving material wealth, they remain in the world constantly, whether or not there is a buddha. As for the giving of Dharma, it can only exist in an era when there has been a buddha. Therefore one ought to realize that the giving of Dharma is extremely difficult. How is it that it is difficult? Even one who is a pratyekabuddha possessed of the marks [of a great man] is still unable to speak Dharma. It is only when he proceeds along on his alms round and flies up into the sky performing transformations, that he is able thereby to convert people.
Then again, from the giving of Dharma, one is able to generate the giving of material wealth as well as reach to the position of a hearer, a pratyekabuddha, a bodhisattva and finally, to reach buddhahood.
Moreover, in carrying out the giving of Dharma, one is able to distinguish all dharmas: outflow and non-outflow dharmas, form dharmas and formless dharmas, conditioned and unconditioned dharmas, wholesome, unwholesome and neutral dharmas, eternal dharmas and non-eternal dharmas, existent and non-existent dharmas, [recognizing that] all dharmas whatsoever, [from the standpoint of] the reality mark, are pure, irrefutable, and indestructible. All dharmas such as these, if one speaks in brief, constitute a treasury of eighty-four thousand dharmas. If one speaks of them extensively, they are countless. Distinguishing and completely understanding all of the different categories such as these comes from engaging in the giving of Dharma.
These two kinds of giving together constitute what is known as dana. If one carries on these two kinds of giving as one seeks to become a buddha, then one will be able to cause people to succeed in reaching the buddha way. How much the more so will it be able to bring about any other result.