大般涅槃經義記 8.101

8.101

上來喻佛，下喻菩薩，「如彼野干，百年不能」舉劣顯勝，明二乘人不能吼也。「若師子子，三年能吼」辯勝過劣，喻明菩薩能師子吼。

The preceding parts used the lion as a metaphor for the Buddha; the following uses it as a metaphor for the bodhisattva. "Like that jackal who cannot do so even after a hundred years" adduces the inferior to make evident the superior, clarifying that people of the two vehicles cannot roar. "Whereas a lion's cub can roar after three years" explains the superior surpassing the inferior, metaphorically clarifying that the bodhisattva can make the lion's roar.