7.3.19
हृद्भगसिन्ध्वन्ते पूर्वपदस्य च
Operational rule vidhi
The वृद्धि is substituted for the first vowels of both (the first and second) members in a compound ending with 1. हृद् 2. भग and 3. सिन्धु before a तद्धित affix having an indicatory ञ् , ण् or क् .
Word by word (padaccheda)
Right context हृद्भगसिन्ध्वन्ते saptamī · ekavacanaTarget पूर्वपदस्य ṣaṣṭhī · 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").
- Target Ṣaṣṭhī (6th case): names what gets replaced, "in place of X" (1.1.49 षष्ठी स्थानेयोगा).
- 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
हृद्भगसिन्ध्वन्ते पूर्वपदस्य च
Pāṇini leaves out words that carry over from earlier sūtras. Expand to see the rule as a reader actually understands it.
Commentary
The वृद्धि is substituted for the first vowels of both (the first and second) members in a compound ending with 1. हृद् 2. भग and 3. सिन्धु before a तद्धित affix having an indicatory ञ् , ण् or क् ।
As सुहृदयस्येदं = सौहार्दम्, सौभाग्यम्, दौर्भाग्यम् सौभागिनेयः (= सुभगाया अपत्यं), दौर्भागिनेयः 4.1.126. The words सुभगा and दुर्भगा occur in the Kalyanadi class 4.1.126, and the affix ढक् and इन् augment are added. सुभग also occurs in Udgatri class 5.1.129. That word, however, does not get the Vriddhi in the second member, As महते सौभगाय ॥ This is a Vedic anomaly. Similarly from सक्तुसिन्धवः (= सक्तुप्रधानाः सिन्धवः) we have साक्तुसैन्धवः (= सक्तुसिन्धुषु भवः) so also पानसिन्धवः ॥ The word सिन्धु occurs in Kachchhadi class, and सैन्धवः is formed by अण् ॥ The Tadanta-rule applies to words formed there-under.
The words सुहृद् and दुर्हृद् are anomalously formed by 5.4.150. But the reading adopted by Kasika is सुहृदयस्येदम्; so the word hridaya is changed to hrid by 6.3.50 or 6.3.51. The word sindhu means 'a country', 'a river' or 'an ocean'.
Śrīśa Chandra Vasu, The Ashtadhyayi of Panini (1897), via ashtadhyayi.com.