俱舍論疏 15.64

15.64

論「四由所因善根斷故」，此是所因斷故捨。戒之所因，所謂三種善根，善根既斷戒亦隨捨。

On the text "Fourth, through the severance of the wholesome roots that served as the cause": this is abandonment because the cause has been severed. The cause of the precepts refers to the three wholesome roots; once the wholesome roots are severed, the precepts are abandoned accordingly.