After bahu , the augment yiṭ is added to iṣṭha and bhū is the substitute of bahu,
As भूयिष्ठः ॥ This augment यिट् debars the lopa substitution, of the last sutra, in the case of इष्ठ ॥ The इ in यिट् is for the sake of pronunciative, the augment being य ॥ Or इष्ठ may be taken to have lost its इ by the foregoing sutra, and to the ष्ठ, the augment यि may be added.,