Ukkacelasutta

Suttapiṭaka · Saṁyuttanikāya · Mahāvaggasaṁyutta · Vol. 19 · Section 744

[744] Bhikkhus, just as, when a great tree stands possessed of heartwood, the larger branches (khandhā) might break off, even so, bhikkhus, while the great Saṅgha of bhikkhus stands possessed of heartwood, Sārīputta and Moggallāna have attained final Nibbāna. What, bhikkhus, could be obtained here in this regard? Whatever is born, come to be, conditioned, subject to disintegration — that it should not disintegrate: such a possibility does not exist. Therefore, bhikkhus, dwell with yourselves as an island, with yourselves as a refuge, with no other refuge; with the Dhamma as an island, with the Dhamma as a refuge, with no other refuge.

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.