瑜伽論記 5.370

5.370

若行趣不淨者，別影顯趣淨。亦趣於善趣者，影顯趣惡趣。

The phrase 'if practice proceeds toward impurity' implicitly reveals by contrast proceeding toward purity. 'Also proceeds toward the good destinies' implicitly reveals by contrast proceeding toward the bad destinies.