四明十義書 1.140

1.140

若內觀未成、分別未亡，歷外境時心心相續觀道無間，方入不二之門。

If inner contemplation is not yet completed and discrimination has not perished, then only when traversing external objects with 'thought after thought succeeding each other and the path of contemplation without interruption' does one enter the non-dual gate.