Bankei wrote:Ancient and Modern Theravadins claim merit can be transferred to others.
This is a practice among Mahayana Buddhists and it is predominant among Theravadins in Buddhist countries, but it is not a teaching of the Buddha or early Theravada commentators. Apparently (I found a source through Google) which claims that it is explicitly rejected in the Kathavatthu
, but despite this, it is strangely mentioned in a text of a later date, the Buddhapadana. It seems like Theravada Buddhism over time was influenced somewhat by trends in Mahayana practices. I think Ven. Dhammanando would be able to say more in detail on this and give you a better answer.
The Dhammapada seems pretty explicit about rejecting the idea of transferring merit (Dhp 165):
Evil is done by oneself,
by oneself is one defiled.
Evil is left undone by oneself,
by oneself is one cleansed.
Purity & impurity are one's own doing.
No one purifies another. No other purifies one.
The mere idea of even considering "transferring" merit seems to miss what merit is, conflating it with a common superstition.
As Accesstoinsight.org's glossary
puñña [pu~n~na]: Merit; worth; the inner sense of well-being that comes from having acted rightly or well and that enables one to continue acting well.
This is distinguished from the common Asian Buddhist misunderstanding of kamma as some kind of mystical "stuff" you carry with you, like a kind of external or paranormal energy or substance that can be stored or transferred. But kamma is simply action, and this action is cetana, that is, intent, and punna is simply the inner sense of well-being that comes from wholesome action.