8.3.103
युष्मत्तत्ततक्षुःष्वन्तःपादम्
Operational rule vidhi
The स् standing in the inner half of a stanza is changed to ष् before the त of त्वम् etc. and युष्मद्.
Word by word (padaccheda)
Right context युष्मत्- तत्- ततक्षुःषु saptamī · bahuvacanaSubstitute / term अन्तःपादम् prathamā · ekavacana
- Right context Saptamī (7th case): "when X follows", the operation applies to what precedes (1.1.66 तस्मिन्निति निर्दिष्टे पूर्वस्य). Also a condition or domain ("in the sense of").
- Substitute / term Prathamā (1st case): in operational rules, the substitute or the thing introduced; in definitions, the term or its referent.
Full reading
युष्मत्-
Pāṇini leaves out words that carry over from earlier sūtras. Expand to see the rule as a reader actually understands it.
Commentary
The स् standing in the inner half of a stanza is changed to ष् before the त of त्वम् etc. and युष्मद्।
The word युष्मद् here means the substitutes त्वम्, त्वाम्, ते, तव. As अग्निष्ट्वं, नामासीत् ॥ त्वा, अग्निष्ट्वो वर्द्धयामसि ॥ ते, अग्निष्टे विश्वमानय ॥ तव, अप्स्वग्ने सधिष्टव, (Rig VIII.43.9) ॥ तत्, अग्निष्टद्विश्वमापृणाति, (Rig X. 2.4) ततक्षुस्, द्यावापृथिवी निष्टतक्षुःषु ॥ अन्तः -पादमिति किम्, नित्यमात्मनो विदाभूदग्निस्तत्पुनराह जातवेदो विचर्षणिः ॥
Why do we say in the inner half of a stanza ? Observe यन्म आत्मनो मिन्दाभूदग्नि स्तत्पुनराह जातवेदा विचर्षणिः ॥ Here the word अग्निः is at the end of the first stanza while तत् is at the beginning of the second stanza, therefore the स् of अग्निस् is not in the middle of a stanza.
Śrīśa Chandra Vasu, The Ashtadhyayi of Panini (1897), via ashtadhyayi.com.