Guardianship from generation to generation.

In the Will and Testament which He left as His final blessing and guidance for the Baha'i community the believers of the world have been given the charter of their evolving Faith. By that momentous document 'Abdu'l-Baha revealed the continuity of divine guidance for human affairs throughout this cycle in the succession of the station of Guardianship from generation to generation.

To this station He attributed the sole power and authority to interpret the Baha'i Sacred Writings, and this station He joined to the Universal House of Justice instituted by Baha'u'llah by making each successive Guardian its chairman for life.

The Baha'i World, Vol. 9, Page 738

https://bahai-library.com/docs/bw/usnsa_bahai_world_9.txt