(The substitution of ṣ for s to be taught hereafter, will take place) for all roots up to sit exclusive in parinivibhyaḥ sevasitasayasivusahasuṭstusvañjām [[8.3.70]], even when the augment aṭ intervenes (between the sa and the efficient letter).,
The root सित् occurs in sutra 8.3.70. Thus 8.3.65 teaches ष change: as अभिषुणोति, परिषुणोति, विषुणोति, निषुणोति ॥ So also when अट् intervenes; as अभ्यषुणोत्, पर्यषुणोत्, व्यषुणोत्, न्यषुणोत् ॥ The force of अपि is that the change takes place even when the augment अट् does not come, i. e. in cases other than the augment.,