रुदश्च पञ्चभ्यः

Operational rule vidhi

A सार्वधातुक-पित्-अपृक्त-हल्-प्रत्यय that follows the verbs रुद्, स्वप् , श्वस्, प्रण्, जक्ष् gets an ईट् आगम.

Word by word (padaccheda)

Left context रुदः pañcamī · ekavacanaIndeclinable च avyayaLeft context पञ्चभ्यः pañcamī · bahuvacana

Left context Pañcamī (5th case): "after X", the operation applies to what follows (1.1.67 तस्मादित्युत्तरस्य). Also used for limits and sources.
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

रुदः च पञ्चभ्यः

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

Commentary

After रुद् and the four roots that follow it, comes the augment ईट् consisting of a single consonant.
As अरोदीत्, अरोदीः, अस्वपीत् and अस्वपीः, अश्वसीत्, अश्वसीः, प्राणीत्, प्राणीः, अजक्षीत्, अजक्षीः ॥ Why of these five only? Observe अजागर् भवान् ॥ Why an aprikta affix? Observe रोदिति ॥ The word रुदः is singular, though it ought to have been plural.

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