ह्रु ह्वरेश्छन्दसि

Operational rule vidhi

ह्रु is substituted for ह्वर् in the छन्दस् (Vedas) before the Participial-affix.

Word by word (padaccheda)

Word ह्रु Target ह्वरेः ṣaṣṭhī · ekavacanaRight context छन्दसि saptamī · ekavacana

Word Case not marked in the source data.
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. Hover or tap one to see its card.

Full reading

ह्रु ह्वरेः छन्दसि

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

Commentary

ह्रु is substituted for ह्वर् in the छन्दस् (Vedas) before the Participial-affix.
As ह्रुतस्य चाह्रुतस्य च, आह्रुतमसि हविर्धानम् (Vaj San. I.9). But ह्रुतम् in secular literature.

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