法華義疏 1.104

1.104

今引二經，據本迹通之。一、《涅槃經》，據本而釋，阿難多聞士，自然能解了是常及無常；既自然解，亦自然得聞。二、依《報恩經》，據迹而解，佛重而說方乃得聞。

We now cite two scriptures to resolve this based on the fundamental and the trace: First, the Nirvāṇa Sūtra explains it based on the fundamental: Ānanda is a scholar of broad learning who spontaneously understands what is permanent and impermanent; since he spontaneously understands, he also spontaneously heard it. Second, according to the Bao'en jing, it is explained based on the trace: the Buddha repeated it for him, and only then did he hear it.