首楞嚴義疏注經 1.214

1.214

下云「十方薄伽梵，一路涅槃門。」直道無異，通至寶所，故云一門清淨果海。眾德具足，故曰莊嚴。真三摩地，因行所履故名為路。

Below, it says: "The Bhagavats of the ten directions, one road to the gate of nirvāṇa." The direct path is without divergence and leads straight to the treasure trove; hence it is called "a single gate." The pure ocean of fruition is fully endowed with all virtues; hence it is called "adorned." The true samādhi, being that which is trodden through causal practice, is therefore called a "path."