Khuddakavatthuvibhaṅga › Mavmenabarivāra

Abhidhammapiṭaka · Vibhaṅga · Vol. 35 · Section 864

[864] Therein, what is obstinacy (thambha)? That which is obstinacy, being obstinate, the state of being obstinate, hardness (kakkhaḷiya), roughness (phārusiya), unbending straightness of mind (ujucittatā), lack of pliancy (amudutā) — this is called obstinacy.

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.