Parinibbānasutta

Suttapiṭaka · Saṁyuttanikāya · Sagāthāvaggasaṁyutta · Vol. 15 · Section 623

[623] When the Blessed One had attained final Nibbāna (parinibbāna), simultaneously with his final Nibbāna, Sakka, lord of the devas, spoke this verse: "Impermanent indeed are formations (saṅkhārā), their nature is to arise and pass away; having arisen, they cease; the stilling of them is bliss."

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.

This passage also appears in 1 other place

Vol. 10 · Section 147 — Mahāparinibbānasutta