摩訶止觀 7.84

7.84

若禪思時，心多覺觀，遍緣三毒，當用數息為治。數若不成，即知心去，去即追還，從初更數。防散錄心，此為良治。以心住故，或發欲界定乃至七依定皆能入。若不得般若方便，成凡夫法；若得方便，成摩訶衍。故《請觀音》云：「若數息心定，毛孔見佛，住首楞嚴，得不退轉。」是為數息開解脫門，即與三藏八定相應，乃至與無作八定相應。是為事油助增道明。

When engaged in dhyāna contemplation, if the mind has many discursive thoughts and broadly conditions the three poisons, one should use counting breaths as the remedy. If counting fails, one knows the mind has wandered; when it has wandered, one brings it back and counts again from the beginning. Guarding against distraction and gathering the mind, this is an excellent remedy. Because the mind abides, it may give rise to desire-realm dhyāna, and one is able to enter all the way up to the seven supporting dhyānas. If one does not attain the skillful means of prajñā, it becomes an ordinary person's practice; if one attains skillful means, it becomes the Mahāyāna. Therefore the Qing Guanyin jing says: 'If through counting breaths the mind becomes settled, one sees the Buddha in every pore, abides in the Śūraṅgama, and attains non-retrogression.' Thus does counting breaths open the door of liberation, immediately according with the eight dhyānas of the Tripiṭaka teaching, up to according with the eight unconditioned dhyānas. This is phenomenal oil assisting to increase the light of the path.