首楞嚴義疏注經 5.404

5.404

未幾，猶在近也。依教觀察，受教未久即證無生。由觀生滅證不生滅，故見東方不動佛國。我身及器咸即本覺妙明元體，故云發光洞徹無礙。

'Not long' means still close in time. Observing according to the teaching, not long after receiving the teaching he realized the non-arising. Through contemplating arising and cessation he realized non-arising and non-cessation; therefore he saw the Eastern Buddha-Land of Akṣobhya ('Immovable'). My body and the vessel[-world] are both entirely the original substance of the wondrous clarity of original awakening; hence it says 'emitted light, thoroughly transparent and unhindered.'