What is Buddhism view on Ancestor Worship? Are there any references which talk about it? Do ancestors occupy any plane/realm ? How to explain the ancestors who come in dreams? Is it manifest of mind?
Ancestor worship, or veneration of the dead, is more of a cultural phenomenon than a religious one (though religions can also influence culture, so it can be difficult to pinpoint the source of different religious/cultural elements).
The practice is most common in countries that also happen to have a larger share of Buddhists, though there's not a huge connection between Buddhism itself and the practice.
Śrāddha is referenced in the Pāli canon, though in a Buddhist context the word has a meaning closer to the notion of "faith". But the word itself has an earlier meaning in the Hindu context, where it was more specifically applied to ancestor worship:
In the Hindu religion, it is the ritual that one performs to pay homage to one's ancestors (Sanskrit: pitṛs), especially to one's dead parents.
Given Buddhism's origins in India, it's easy to see the connection between the cultural practice of ancestor worship and the linguistic fluidity of a single word used to describe both the practice and an early Buddhist concept. Ultimately, though, there doesn't appear to be any direct call for ancestor worship within Buddhist doctrine (which makes sense, given the overall emphasis on our present actions and not clinging to the past).
Honor and gratitude, sacrifices toward those having been first and unavoidable paved ones way is a matter of gratitude and the group of departed is one of the relations where a householder is obligated to. The kind of relations, obligated to for everyone are:
- wife & children
- slaves & workers
- guest duties
And of course, to go after ones duties in regard toward ones ancestors, is praised by wise and foremost of them by the Sublime Buddha.
Since modern people have forfotten the basics, have no regards toward that of which was in any culture usual, since marxism, wrong view, took over the main, my person will not go more into deep and those with certain Nissaya will be good reminded by only this.
In traditional countries, btw. are those days now used for especially sacrifices toward and the welfare of ones departed relatives (of the last seven generations usually)
[Note that this isn't given for stacks, exchange, trades binding in the world, but for escape from this wheel]