坐禪三昧經 1.57

1.57

問曰：「若餘不淨、念佛、四等觀中，亦得斷思覺，何以故獨數息？」

Question: "If discursive thoughts can also be severed in the other contemplations—such as the contemplation of impurity, mindfulness of the Buddha, and the four immeasurables—why is it only through counting the breath?"