All Wudi had created with his good deeds was only worldy merit, for he had performed them with a deluded mind. Worldy merit, was according to Bodhidharma:
"Small fruits of human & deva realms,
Grown from seeds with remainder;
Like a shadow that follow its from,
Which although exists but it unreal."
If one clings to the concept of Dana - whether it is a person giving, object given or person receiving, then whatever merit one gains is illusionary, leading one to temporary happiness but suffering in the end. It does not matter whether you expect anything in return or not.
True merit is only attained when you see in your mind that there is no giver, no object, no receiver & therefore no merit gained whatsoever. In other words, it is transcendal merit. As Bodhidharma described:
"Pure & perfect wisdom,
With an intrinsically empty body;
Such a kind of merit,
Cannot be gained by worldly means."
We all know that before you can realize the unconditioned reality of Nibbana, you do need all sorts of worldly good deeds & practices to help you towards that goal. Whether it is the Theravada or other Mahayana schools, they all share the same ideology. Even Shen Xiu, Hui Neng's compatriot under the 5th patriach also teach in the same manner. That's why he once said that:
"To refrain from all evil is Sila,
To cultivate all good is Prajna;
To purify one's mind is Samadhi."
Very standard Dhamma practice. Great. But why can't people attain Buddhahood following this teaching? The problem lies with the nature of sentient beings, which grasps on to everything, getting stuck to whatever they are doing & become unable to progress. That's where the unconventional Chan teaching comes in. Chan pulls the mat out from under you, completely taking out the root of grasping within you - your own mind. Every teaching of Chan does not deviate from this spirit. Thus Hui Neng replied to Shen Xiu's katha saying:
"Not to think in a wrong way is Sila,
Not to think in an ignorant way is Prajna,
Not to think in a confused way is Samadhi;
Like diamond it neither increases nor decreases,
Whether coming or going it never leaves Samaya."
This gatha teaches us not to think in a way which is not in accordance with the emptiness of the mind, which leads to grasping & consequently stagnation. It is no different from Bodhidharma's teaching to Emperor Liang Wudi. Therefore the Dana practiced by a Chan practitioner is not the same as the Dana practiced by those from other schools.
After all being said, I want to clarify that I'm not asking anybody to follow the Chan school, but I just found it appropriate to state the Chan position on Dana & worldy merit since I practice Chan. The reader can then compare this to his or her own understanding of this subject & come to your own conclusions. To end this posting I'd like to tell another short Zen koan abt the Layman Pang:
After Layman Pang attained enlightenment, he took all his wealth, put them on a boat & sailed it out to sea. He then let all of it sink to the bottom of the sea. When he returned to land, somebody asked him:
"Why did you let all that wealth go to waste? Why not use it for Dana?"
To this Pang replied:
"No way! Dana was precisely the cause of my suffering for too many past lives!"
Can you now understand why Layman Pang said that?