Mahāparinibbānasutta

Suttapiṭaka · Dīghanikāya · Mahāvagga · Vol. 10 · Section 147

[147] When the Blessed One had attained final Nibbāna, simultaneously with the final Nibbāna, Sakka, lord of the devas, spoke this verse: Impermanent indeed are conditioned things (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English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.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. 15 · Section 623 — Parinibbānasutta