Sattajaṭila Sutta
At one time the Blessed One was dwelling at Sāvatthi, in the Eastern monastery, in the Migārāmatupāsāda, and in the evening, having emerged from seclusion was sitting near the gateway. King Pasenadi approached and paid homage, and while he was sitting there, seven Jatiḷā, seven Nigaṇṭhā, seven Acelakā, seven Ekasāṭakā, and seven Paribbājakā passed by not far away.
The king got up from his seat, arranged his robe over one shoulder, knelt on his right knee, and raised his hands in reverence, announcing his name as the king Pasenadi.
Having sat down again he said to the Blessed One that those men were Arahants or had entered upon the path to Arahantship.
The Buddha says that it is difficult for a householder like the king who enjoys sensual pleasures to know if they are Arahants or have entered on the path of Arahantship.
It is by living together with someone for a long time that their virtue can be known, and that only by one who is attentive and wise.
It is through dealings with someone for a long time that their honesty can be known, and that only by one who is attentive and wise.
It is in times of adversity for a long time that a person’s fortitude can be known, and that only by one who is attentive and wise.
It is by discussion with someone for a long time that their wisdom can be known, and that only by one who is attentive and wise.
The king praised the Blessed One’s explanation, adding that his spies moved about the country gathering information without being known.
The Buddha then uttered two verses warning that a man is not easily know by outward appearance and that one should not make a quick appraisal. Like earrings of clay or brass coins coated with gold leaf, some men move about outwardly composed, but inwardly impure. S.i.77.
The discourse is repeated at Ud.64.