7.3.21
देवताद्वन्द्वे च
Operational rule vidhi
Before a तद्धित affix having an indicatory ञ् , ण् or क् , the वृद्धि is substituted for the first vowels of both members of द्वन्द समास of the names of देवता-s.
Word by word (padaccheda)
Right context देवताद्वन्द्वे saptamī · ekavacanaIndeclinable च avyaya
- 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").
- Indeclinable An avyaya such as च "and", वा "optionally", न "not".
Dotted words are technical terms, dashed ones pratyāhāras (names for classes of sounds or affixes). Hover or tap one to see its card.
Full reading
देवताद्वन्द्वे च
Pāṇini leaves out words that carry over from earlier sūtras. Expand to see the rule as a reader actually understands it.
Commentary
Before a तद्धित affix having an indicatory ञ् , ण् or क् , the वृद्धि is substituted for the first vowels of both members of द्वन्द समास of the names of देवता-s।
As अग्निमारुती in अग्निमारुतीमनड्वाहीमालभेत् ॥ आग्निमारुतं कर्म ॥ The rule applies to Dvandas relating to hymns (सूक्त) and sacrificial offerings (हवि). Therefore, not here, स्कान्दविशाखौ देवतेऽस्य = स्कान्दविशाखः 4.2.24. So also ब्राह्मप्रजापत्यम् by ण्य from ब्रह्मप्रजापती ॥ See 6.3.26.
The short इ in the आग्नि in आग्निमारुत, आग्निवारुणम् is by 6.3.28. A compound relates to a sukta, which worships a deva through hymns; and that by which a 'havis' is determined, is a compound relating to sacrificial offering.
Śrīśa Chandra Vasu, The Ashtadhyayi of Panini (1897), via ashtadhyayi.com.