The affixes ktavā and ṇamul are added to the roots bhū 'to be', when the word tūṣṇīm 'silently' is in composition.,
Thus तूष्णीम्भूय, तूष्णीं भूत्वा, or तूष्णीम्भावम् 'having become silent'. The repetition of भू in this sutra, shows that the anuvritti of कृ does not run into it and altogether ceases.,