Goliyānisutta

Suttapiṭaka · Majjhimanikāya · Vol. 13 · Section 215

[215] Friends, a forest-dwelling bhikkhu should be one with mindfulness (sati) established. If, friends, a forest-dwelling bhikkhu is muddled in mindfulness, there will be those who say of him: "What indeed is the point of this venerable forest-dweller's living alone in the forest at his own free will, when this venerable one is muddled in mindfulness?" — there will be those who say this of him. Therefore a forest-dwelling bhikkhu should be one with mindfulness established.

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.

This passage also appears in 2 other places