Reti acknowledged he could have voted "yes", and left it to the public to decide on the issue.
"I'm here to do the tough stuff. That may have been easier but it's not what I'm here to do."
Of Northland's six MPs, Reti was the only "no" vote. National's Matt King, Labour's Kelvin Davis and Willow Jean Prime, and NZ First's Winston Peters and Shane Jones voted for the legislation to go through.
Reti had never spoken on the issue when it had previously been debated in Parliament. When he did rise to speak this week, he told Parliament he was speaking with three voices - as a doctor, as Maori and as a citizen.
He spoke of family of seriously ill patients having confidence their loved one's doctor was "working as hard as they can to return our loved one to the very best physical, mental, and social condition possible".
"There are no other options. There is no other agenda. There is no other step. The backstop that commands the doctor is to return that person to the best condition possible. If this bill passes, another option is created.
"I don't want an option of anything other than the very best care I can provide."
Speaking from a Te Ao Māori perspective, Reti said he believed "we reach here beyond where we are meant to reach".
"Just because we can doesn't mean we should."
From his citizen's perspective, Reti cited composers Franz Schubert, Ludwig Beethoven and Johann Bach, who all suffered qualifying conditions yet produced great works in the months before their deaths.
Of those, he said: "Under euthanasia, this brightness would be gone from the world."
Other Northland MPs did not speak in the latest debate on the issue. The architect of the Bill, Act's David Seymour, told Parliament the proposed law was "about how we treat the most vulnerable in our society".
He said those wanting to end suffering at the end of life needed the courage of Parliament's support to allow them to do so. "We must give them choice."
