Men of purified souls, O king, can stay with ease upon Yoga-contemplation which is like the sharp edge of razor. Persons of impure souls, however, cannot stay on it.
सुस्थेयं क्षुरधारासु निशितासु महीपते। धारणासु तु योगस्य दुःस्थेयमकृतात्मभिः॥