瑜伽論記 4.333

4.333

經言：以慈俱行心等者，第二釋四無量差別，經文有三：初、釋通經；次、問答辨因釋別經；後、結成聖行。

Regarding the sūtra's words, "with a mind conjoined with benevolence, and so forth": this is the second part, explaining the differences among the four immeasurables. The sūtra text has three parts: first, explaining the general sūtra; next, distinguishing the causes through questions and answers to explain the specific sūtra; and last, concluding with the establishment of noble practice.