說無垢稱經疏 5.430

5.430

贊曰：三難也。依根學法，名之為乘。總趣三乘，言難解了，名為密意。

Commentary: Third, the objection. Learning the Dharma according to one's faculties is termed a 'vehicle'. Bringing them altogether toward the three vehicles, words difficult to understand and comprehend are termed 'implicit intent' (sandhāya-bhāṣita).