大般涅槃經義記 4.150

4.150

自下第四嘆經殊勝，令人習學，治捨前過。初先法說，「是故當知大乘經典必定淨」者，是謗大乘名邪惡故，當知大乘必定淨也。次喻、後合。

From here on, the fourth [part] praises the excellence of the sūtra to cause people to practice and learn it, counteracting and relinquishing the previous faults. First, it speaks in terms of Dharma: "Therefore one should know that the Mahāyāna sūtras are definitively pure" means that because slandering the Mahāyāna is called wrong and evil, one should know that the Mahāyāna is definitively pure. Next comes the parable, and then the combination.