The tenth sutta of the Atthaka Vagga of the Sutta Nipāta. It was among the suttas preached at the Mahāsamaya in answer to the questions asked of the Buddha by the created Buddha (SNA.ii.548).
It is a long disquisition on the characteristics of a calm sage (upasanta). He is free from craving, anger, etc., is equable and thoughtful, possessed of calm, and walk's in the path of righteous men (SN. vs. 848 61).
The sutta was preached for the benefit of the buddhi caritā. SNA.i.361; MNid. 223.