[818] **One should be truthful, not impudent (sacco siyā appagabbho).** "One should be truthful" means: one should be endowed with truthful speech, one should be endowed with right view (sammādiṭṭhi), one should be endowed with the noble eightfold path; thus, "one should be truthful." "Not impudent" means: there are three kinds of impudence (pāgabbhiya) — bodily impudence, verbal impudence, and mental impudence … this is mental impudence. One in whom these three kinds of impudence have been abandoned, cut off, stilled, tranquilized, rendered incapable of arising again, burnt up by the fire of knowledge (ñāṇa) — he is called "not impudent." Thus, "one should be truthful, not impudent."
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.