Duṭṭhaṭṭhakasuttaniddesa

Suttapiṭaka · Khuddakanikāya · Mahāniddesa · Vol. 29 · Section 80

[80] The Blessed One said: Whatever person, unasked, proclaims his own virtues and observances to others — the skilled declare him one of ignoble character; so too whoever, of his own accord, speaks of himself.

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.