大乘起信論裂網疏 1.23

1.23

有法，即指下文所詮一切眾生心也。說此心真如相，即示大乘體；說此心生滅因緣相，能顯示大乘體相用。令諸眾生生聞思修三慧，乃至究竟成佛，名為大乘信根。有此勝益，故應說也。

"There is a dharma" points to the mind of all sentient beings, which is explicated in the text below. Explaining the aspect of tathatā of this mind shows the essence of the Mahāyāna; explaining the aspect of the causes and conditions of arising and ceasing of this mind can reveal the essence, attributes, and function of the Mahāyāna. Causing sentient beings to give rise to the three wisdoms of hearing, reflecting, and cultivating, up to definitively becoming Buddhas, is named "the faculty of faith in the Mahāyāna." Because it has this supreme benefit, it should be explained.