The Buddha does describe sammā-samādhi as being the 1st to the 4th jhāna a very large number of times in the Suttas. However, from not ever having come across a similar passage (please post if you have), he doesn’t say anything along the lines of “sammā-samādhi (right concentration) is jhāna and nothing else.” Furthermore, he also hasn’t distinctively said that “jhāna is required to attain Nibbāna" or that “without having reached jhāna, Nibbāna is imposssible”(again, please post if you have found such a passage).
To infer such statements as the above in quotation marks, in comparison to what the Buddha has said, would be abrupt conclusions. However, to come to the conclusion that there is more to sammā-samādhi than just jhāna, and that jhāna is not a requirement to attain Nibbāna, simply from the absense of such statements by the Buddha, would also be abrubt conclusions.
So, the questioning is…
While sammā-samādhi (right concentration) is often described in the Suttas as the 1st, 2nd, 3rd and 4th jhānas, does this mean that sammā-samādhi is only jhāna and nothing else?
While it would be thought that jhāna is requirement for attaining Nibbāna, there are many accounts in the Suttas of people spontaneously reaching Nibbāna, possibly without much thorough meditate experience. And, from what we gather so far, the Buddha never said that “jhāna is a requirement for Nibbāna,” or that “Nibbāna is impossible without having reached one or all of the jhānas” (which would have been an important statements to say, at least a few times). So, is jhāna an absolute requirement to attain Nibbāna (and optionally, is it only reaching, masterering, one jhāna or all four)?
Note: If your answer is to be opinion-based, please post to point out things such as errors in deductive reasoning or basic logic, and to provide factual statements. Please try to include as many canonical references to support your statements.