The
Tathāgatakośasūtra (Tib.
De bzhin gshegs pa'i mdzod kyi mdo) is cited by Śāntideva in the
Śikṣāsamuccaya as a source for clearing away vile actions (
pāpaśodhana) through confidence in
emptiness. In the passage quoted, addressed to Kāśyapa, the Buddha enumerates the most extreme forms of the ten unwholesome courses of action—killing a father who is also a solitary sage (
pratyekabuddha), stealing the property of the Three Jewels, raping a mother who is also a saint, falsely accusing the Tathāgata, disparaging the community of noble ones, holding noble ones in contempt, distracting those who wish to hear the Dharma, plotting the five actions of immediate retribution, coveting the rightfully earned wealth of others, and becoming entangled in wrong views. Śāntideva then explains that even a person who has committed all of these worst forms of unwholesome action can be freed from their karmic consequences by being introduced to the Tathāgata's teaching on causes and conditions—the insight that there is no self, no sentient being, no life-force, no person, no agent, and no experiencer of action—together with confidence in the primordial purity of all phenomena; such a person, the text states, will not fall into the lower realms.
No text titled De bzhin gshegs pa'i mdzod kyi mdo (*Tathāgatakośasūtra) is contained in the Tibetan Kangyur, and its identification with the Tathāgatagarbhasūtra—sometimes assumed on the grounds that the Chinese character zang 藏 can render both garbha and kośa—has not been substantiated; the content of the passage bears no resemblance to the Tathāgatagarbhasūtra's nine similes of buddha-nature. Tauscher (2021), addressing the same citation as it appears in the early Tibetan sūtra anthology Mdo sde brgyad bcu khungs, likewise finds no confirmed match and tentatively suggests the text may survive, if at all, only in a Chinese work, the [Dafangguang] Rulai mimizang jing 大方廣如來祕密藏經 (Taishō 821), though no corresponding passage could there be identified either. The Tathāgatakośasūtra is therefore best treated as an unidentified or lost text.
