大般涅槃經義記 5.335

5.335

自下第五明四無量實益不虛，迦葉先作無益之難，後佛明益。難中有三：一明慈觀不真、二「若非虛妄，實與樂」下明慈無實益、三「若實不得樂，如佛所說我念往」下執因疑果。

Below is the fifth part: explaining that the four immeasurables have real, not futile, benefits. Kāśyapa first raises an objection regarding their having no benefit, and then the Buddha clarifies their benefit. In the objection there are three points: first, explaining that the contemplation of benevolence is not real; second, from "If it is not false and truly gives joy..." onward, explaining that benevolence has no real benefit; third, from "If they truly do not obtain joy, as the Buddha said, 'I remember in the past...'" onward, clinging to the cause to question the fruit.