खिदेश्छन्दसि

Operational rule vidhi

There is optionally the substitution of आ in the room of the diphthong of the verb खिद् 'to suffer pain', in the छन्दस्.

Word by word (padaccheda)

Target खिदेः ṣaṣṭhī · ekavacanaRight context छन्दसि saptamī · ekavacana

Target Ṣaṣṭhī (6th case): names what gets replaced, "in place of X" (1.1.49 षष्ठी स्थानेयोगा).
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").

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

खिदेः छन्दसि

Pāṇini leaves out words that carry over from earlier sūtras. Expand to see the rule as a reader actually understands it.

Commentary

There is optionally the substitution of आ in the room of the diphthong of the verb खिद् 'to suffer pain', in the छन्दस्।
The word विभाषा is understood here. Thus चित्तं चिखाद or चिखेद ॥ In secular literature we have चित्तं खेदयति ॥

Śrīśa Chandra Vasu, The Ashtadhyayi of Panini (1897), via ashtadhyayi.com.