Prasthānatraya names the triple canon on which every school of Vedānta must ground itself: the Upaniṣads as revelation, the Brahma Sūtras as reasoned summary, and the Bhagavad Gītā as teaching remembered from the epic. A founder of a school was expected to write commentaries on all three, and the great teachers did.
Prasthānatraya
The “three starting points” of Vedānta: the Upaniṣads, the Brahma Sūtras and the Bhagavad Gītā.
Also: Prasthana traya