उदि कूले रुजिवहोः

Operational rule vidhi

The affix खश् comes after the verbs रुजि 'to break into pieces' and वह् 'to carry', when preceded by the उपसर्ग उत् and the word कूल 'bank' is in composition with them as the object.

Word by word (padaccheda)

Right context उदि saptamī · ekavacanaRight context कूले saptamī · ekavacanaTarget रुजि- वहोः ṣaṣṭhī · dvivacana

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).

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

उदि कूले रुजि-वहोः

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

Commentary

The affix खश् comes after the verbs रुजि 'to break into pieces' and वह् 'to carry', when preceded by the उपसर्ग उत् and the word कूल 'bank' is in composition with them as the object.
Thus कूलमुद्रुजति = कूलमुद्रुजः 'breaking down banks' (such as a chariot, river, elephant, &c.); कूलमुद्वहः 'tearing up or carrying away the bank'.

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