瑜伽論記 19.185

19.185

初中，云於生死中行正行者，謂如病者，於所有病於辛苦藥者，於生死中行難行行，如為治病服辛苦藥。

In the first part, where it says 'practicing correct practice within saṃsāra', it means: just as a sick person, regarding all diseases, [takes] bitter medicine, so within saṃsāra one practices practices that are difficult to practice, just like taking bitter medicine to cure disease.