Dhammagiri Vesak: Great Final Nibbāna of the Buddha
The Buddha attained Final Nibbāna lying between the twin Sāla trees in the Sāla grove of the Mallas of Kusināra. 500 monks, all the inhabitants of nearby Kusināra town, and devas from 10 world systems had assembled to witness the event.
Although dying from a severe illness with excruciatingly painful feelings, the Buddha continues teaching and consoling everyone present until his last moments. He finally enters all the different jhānas for a last time, and, just when emerging from the 4th jhāna, he attains the 'Anupādisesā Nibbānadhātu' ('Nibbāna Element without Remainder').
Ven Anuruddha, the foremost disciple in divine eyesight and comprehension of other persons' minds, uses his psychic powers to directly observe the Buddha's mind at that moment. He utters the following verse:
"There was no breathing in or out,
Unmoving, and intend on peace,
The Such-One with a steadfast mind,
The One with vision is released.
Detached, his heart remained unbowed;
Equanimous, he did endure the pain.
Just like a fire gone out from lack of fuel,
His heart is totally released."
Dīgha Nikāya (Long Discourses of the Buddha), #16.6
Ajahn Dhammasiha offers some reflections on the occasion.