The s is elided when it is preceded by a jhal consonant (all consonant except semi-vowels and nasals) and is followed by an affix beginning with a jhal consonant.,
Thus अभित्त for अभित्स्त, अभित्थाः for अभित्स्थाः ॥ So also अच्छित्त, अच्छित्थाः, अवात्ताम्, अवात्त ॥ The last example may also be explained by 7.4.49; the elision of the स of सिच् being considered as asiddha, the स् of the root is changed to त् ॥
Why do we say 'of a jhal consonant'? Observe अमंस्त and अमंस्थाः ॥ Why do we say followed by a jhal consonant ? Observe अभित्साताम्, अभित्सत ॥
The स of this sutra refers also to the स of सिच्; no other स is elided. As सोममसुत् स्तोता; दृषत् स्थानम् ॥ Here the स of स्तोता and स्थानं, though preceded by a jhal letter त्, could never be elided as they do not form portion of one word.,