Of all the various marvellous tathagatagarbha sutras, perhaps the most ‘cataphatic’ (affirming of the real nature of Reality) is the Angulimaliya Sutra. In this little-known but vital Mahayana sutra (very different from the Pali Angulimala Sutta) , the great bodhisattva, Angulimala, teaches the deeper truths regarding the Buddha Essence / Buddha Principle (tathagatagarbha or buddha-dhatu) to Manjushri and other high-level bodhisattvas – and he does so most forcefully. He takes no hostages!
Here is a link (via the Wayback Machine) to a website I set up many years ago (long since defunct, sadly – not of my choosing!) and which contains a very lengthy extract from this superb sutra. The translation of it here was commissioned by myself (Dr. Tony Page) and carried out by Stephen Hodge. Please enjoy the vigorous and unequivocal high-level teachings on the limitations of the notion of Emptiness, and the reiterated Reality of the tathagata-garbha (the perfect indwelling Buddha Essence). To turn from one page to the next, go down to the bottom of the page where it says ‘Tathagatagarbha 17’ and click on that; then on the next page, click on ‘Tathagatagarbha 18’ and so on to progress page by page through the long extracts from the sutra. https://web.archive.org/web/20110604041748/http://www.webspawner.com/users/tathagatagarbha16/index.html
The Nirvana Sutra 