瑜伽論記 13.348

13.348

是名第四損伏等者，染種未斷，能助善無記種子得果，由永害染種，即是永害助伴，故能損伏善無記種不能生果，故名永害助伴損伏。

Regarding "This is called the fourth weakening and suppression, etc.": when defiled seeds are not yet severed, they can assist wholesome and indeterminate seeds in obtaining fruition; through permanently destroying defiled seeds, that is permanently destroying their companions, hence they can weaken and suppress wholesome and indeterminate seeds so that they cannot produce fruition; therefore it is called weakening and suppression through permanently destroying companions.