Vesākha - The Anniversary of the Buddha’s Birth and Enlightenment.

[Bhikkhu Pesala]

Tradition says that the Buddha’s birth, Enlightenment and death (parinibbāna),¹ took place on the full-moon day of Vesākha.

¹ However, see the Mahāparinibbāna Sutta, wherein the Buddha tells Māra, “Three months from now I will attain parinibbāna. — Appossukko tvaṃ, pāpima, hohi, na ciraṃ Tathāgatassa parinibbānaṃ bhavissati. Ito tiṇṇaṃ māsānaṃ accayena Tathāgato parinibbāyissatī”ti.

This event apparently occurred while the Buddha was spending his last Rains Retreat at Beḷuva alone with Ānanda as his attendant, which would make the date of his parinibbāna three months later in January.

The Buddha entered upon his final Rains Retreat with just the Venerable Ānanda as his companion. He soon became gravely ill, but suppressed the sickness thinking: “It would not be right for me to pass away without addressing the disciples, without taking leave of the Saṅgha. Let me now, by a strong effort of will, suppress this sickness, and keep hold on life until the allotted time has come.”

This is when the Blessed One gave multiple hints to Ānanda that he could, if he so wished, live until the end of the full lifespan (kappa). Perhaps 120 years is normal with 160 years being the upper limit at that time. The Venerable Ānanda did not take the hint (a point for which he was later criticised at the First Buddhist Council).

After this, Māra asks the Buddha to pass away at once. The Buddha declines Māra’s request, stating that three months from now he will pass away, thus renouncing his remaining lifespan of 40 or at most 80 more years.

This renunciation was the cause of a great earthquake. Then the Buddha rejects Ānanda’s plea to live on, since he cannot go back on his own word. He tell Ānanda to assemble the monks from all around Vesāli to give his final instructions, and tells them that he will pass away in three months.

Since the Buddha stated the same period of three months to Māra and to the monks, these events must have occurred on the same day or the following day. The monks would have assembled on the Pavāraṇa day at the end of the Rains — the Buddha would not have made them break their Rains Retreat. The end of the Rains is in October, so the Buddha's Parinibbāna must have been in January, not in May, and at the age of 80+ not at 80 nor at 81 years of age.

[SarathW]

Do we know when the Vesakha celebration first started?