Sāriputtasuttaniddesa

Suttapiṭaka · Khuddakanikāya · Mahāniddesa · Vol. 29 · Section 900

[900] For a bhikkhu who is repelled [by the world], resorting to an empty seat — the root of a tree, a charnel ground, or in the caves of the mountains.

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.