AN 4.259
Thai 4.263
Araññika Sutta: A Wilderness Dweller
translated from the Pali by
Thanissaro Bhikkhu

"Endowed with [any of] four qualities, a monk isn't fit to stay in isolated forest & wilderness dwellings. Which four? [He is endowed] with thoughts of sensuality, with thoughts of ill will, with thoughts of harmfulness, and he is a person of weak discernment, dull, a drooling idiot. Endowed with [any of] these four qualities, a monk isn't fit to stay in isolated forest & wilderness dwellings.

"Endowed with four qualities, a monk is fit to stay in isolated forest & wilderness dwellings. Which four? [He is endowed] with thoughts of renunciation, with thoughts of non-ill will, with thoughts of harmlessness, and he is a discerning person, not dull, not a drooling idiot. Endowed with these four qualities, a monk is fit to stay in isolated forest & wilderness dwellings."