8.2.35
आहस्थः
Operational rule vidhi
The हकार of 'आह्' is converted to थकार when followed by a झल् letter.
Word by word (padaccheda)
Target आहः ṣaṣṭhī · ekavacanaSubstitute / term थः prathamā · ekavacana
- Target Ṣaṣṭhī (6th case): names what gets replaced, "in place of X" (1.1.49 षष्ठी स्थानेयोगा).
- Substitute / term Prathamā (1st case): in operational rules, the substitute or the thing introduced; in definitions, the term or its referent.
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
आहः थः
Pāṇini leaves out words that carry over from earlier sūtras. Expand to see the rule as a reader actually understands it.
आहः → थः
Replace āhaḥ with thaḥ. Inherited words (anuvṛtti) may add further conditions.
Commentary
For the ह of the root आह् there is substituted थ before a झल् (all consonant except semi-vowels and nasals) letter.
As इदमात्थ, किमात्थ ॥ The word आथ्थ becomes आत्थ by 8.4.55. Why has the last mentioned substitute ध not been ordained here, for this ध would also have given the form आत्थ by चर change, as the थ is also changed to त; and by so doing there would have been only one sutra, instead of two i.e. आहनहो र्ध would have been enough? Making this separate substitute, is for the sake of indicating that the rule 8.2.40, does not apply here. For had 8.2.40, still applied, the substitute ध of the last sutra would have been enough. The त substitute, however, would have been the best.
The word झलि is understood here. Hence there is no change before vowel affixes, as आह, आहतुः, आहुः ॥
Vart:- In the Chhandas, भ is substituted for the ह of हृ and ग्रह ॥ Thus गर्दभेन संभरति; मरुदस्य गृभ्णाति; सामिधेन्यो जभ्रिरे, उद्ग्राभञ्च निग्राभञ्च ब्रह्म देवा अवीवृधन् ॥
Śrīśa Chandra Vasu, The Ashtadhyayi of Panini (1897), via ashtadhyayi.com.