Is there a correlation between vedanta (non-dualism) and Dhamma? Are there references in the Pali-canon to vedanta?
What was before the Buddha? The Vedas and the earliest Upanishads (Brhadaranyaka, Chandogya) came before the Buddha.
A few other Upanishads (Taittiriya, Aitareya, and Kausitaki) and the Nyaya school of logic may have developed around the same time as the Buddha.
If you look at the scholarly dates given in Wikipedia, all Vedanta schools, Samkhya, Yogasutras of Patanjali, Purva Mimamsa school, the rest of the Upanishads (Kena, Katha, Isa, Svetasvatara, Mundaka, Prasna, Mandukya), Brahmasutras and Bhagavad Gita all came after the Buddha's time.
If you read the Vedanta page on Wikipedia, you will find this info:
Vedanta or Uttara Mīmāṃsā is one of the six (āstika) schools of Hindu philosophy.
Some of the better known sub-traditions of Vedanta include:
- Advaita Darshan - established by Adi Shankara (788–820 CE)
- Vishishtadvaita Darshan - established by Ramanujacharya (1017–1137 CE)
- Dvaita Darshan - established by Madhvacharya (1238–1317 CE)
- Bhedabhed (or Dvaitadvait) Darshan - established by Nimbarkacharya (c. 7th century CE)
- Shuddhadvait Darshan - established by Vallabhacharya (1479–1531 CE)
- Achintyabhedabhed Darshan - established by Chaitanya Mahaprabhu (1486–1534 CE)
On the other hand, if you read the Wikipedia page on the Buddha:
The times of Gautama's birth and death are uncertain. Most historians in the early 20th century dated his lifetime as c. 563 BCE to 483 BCE. More recently his death is dated later, between 411 and 400 BCE, while at a symposium on this question held in 1988, the majority of those who presented definite opinions gave dates within 20 years either side of 400 BCE for the Buddha's death. These alternative chronologies, however, have not been accepted by all historians.
So, Vedanta (as a school) came after the Buddha. So you will not find references to Vedanta in the Pali Canon. The only reference is to the three Vedas in the Canki Sutta (MN 95) and Tevijja Sutta (DN 13). The composers of the Vedas are also mentioned in these suttas by name.
I imagined that Advaita Vedanta influenced Indian Mahayana schools, but it turns out that it may be the other way round. Nagarjuna, the founder of the Madhyamaka school, lived around 150 - 250 CE. Asanga and Vasubandhu, the founders of the Yogacara school, lived around 3rd to 4th century CE. This predates all schools of Vedanta.
The best correlation between Buddhism and Vedanta that I can find is from "Vedanta and Buddhism: A Comparative Study" (1995) by Professor Helmuth von Glasenapp:
Nothing shows better the great distance that separates the Vedanta and the teachings of the Buddha, than the fact that the two principal concepts of Upanishadic wisdom, Atman and Brahman, do not appear anywhere in the Buddhist texts, with the clear and distinct meaning of a "primordial ground of the world, core of existence, ens realissimum (true substance)," or similarly.
And another one from "Madhyamika Buddhism Vis-a-vis Hindu Vedanta (A Paradigm Shift)" (1994-95) by Acarya Dharmavajra:
To sum it up, the Vedantic ultimate truth is the existence of an ultimate existence or ultimate reality. Reality here is used as something which exists (skt. satta). However, the Buddhist ultimate truth is the absence of any such satta i. e. ultimately existing thing or ultimate reality.
Certainly, the Vedanta philosophy expounded by Adi-Shankara and even his teacher Gauḍapāda are all centuries after the Pali-Canon or even Nagarguna, but to say that the philosophy of non-dualism is a Buddhist influence on the Indian thought as @ruben2020 implied above is a stretch out of proportion. Ashtavakra Gita predate Buddhism by 400-600 yrs'.
Some may argue that the Gita is not an Advaita Vedanta scripture, but no one would deny that it is non-dual teaching.
The Ashtavakra Gita (Sanskrit in Devanagari: अष्टावक्रगीता; IAST: aṣṭāvakragītā) or the Song of Ashtavakra is a classical Advaita Vedanta scripture. Based on the language structure, this Vedic scripture is also known as Ashtavakra Samhita, and it is dated to be around 1100 BCE to 800 BCE based on the composition style of the Samhita period. The Ashtavakra Samhita documents a dialogue between the Perfect Master Ashtavakra and Janaka, one of the Janaka king of Mithila.
The Pali-Canon is pre Vedanta, I think it is fare to say that, thus there is no reference to Vedanta in it.
That said, it is apparent that both Vedanta and Buddhism borrow a lot of ideas from the ancient Vedic and pre-vedic thoughts so it's not a clear cut.
Alara Kalama the teacher of Buddha was a Sramana and taught a Samkhya philosophy which @ruben claim as a post Buddhist philosophy.