首楞嚴義疏注經 1.440

1.440

真實邊際，即至極義，此即大教所指示處。悔過責，躳遭難未證，蓋由不知此所詣處，即如來藏體也。

"The limit of reality" (bhūtakoṭi) means the ultimate reality; this is precisely where the Great Teaching points. He repents his error and reproaches himself, having encountered calamity without having attained realization, all because he did not know where this leads—namely, the essence of the tathāgatagarbha.