8.3.115
सोढः
Operational rule vidhi
The ष् substitution does not take place in the स् of सोढ form of the root सह.
Word by word (padaccheda)
Target सोढः ṣaṣṭhī · ekavacana
- Target Ṣaṣṭhī (6th case): names what gets replaced, "in place of X" (1.1.49 षष्ठी स्थानेयोगा).
Full reading
सोढः
Pāṇini leaves out words that carry over from earlier sūtras. Expand to see the rule as a reader actually understands it.
Commentary
The ष् substitution does not take place in the स् of सोढ form of the root सह।
As परिसोढः, परिसोढुम्, परिसोढव्यम् ॥ This is an exception to 8.3.70.
Why do we say 'when सह assumes the form of सोढ' ॥ Observe परिषहते, विषहते ॥
Śrīśa Chandra Vasu, The Ashtadhyayi of Panini (1897), via ashtadhyayi.com.