大般涅槃經疏 17.9

17.9

「善男子為諸眾生」下，是第二明慈兼用者。若慈但與樂、悲唯拔苦，則非兼用。今明慈亦拔苦、悲亦與樂。捨中亦二，如文。

From 'Good son, for the sake of all sentient beings' onward, this is the second, explaining the combined function of friendliness: if friendliness only gave happiness and compassion only eradicated suffering, then that would not be combined function. Now it explains that friendliness also eradicates suffering, and compassion also gives happiness. Within equanimity there are also two, as in the text.