6.3.59
एकहलादौ पूरयितव्येऽन्यतरस्याम्
Operational rule vidhi
उद is optionally substituted for उदक before a word beginning with a single consonant and which expresses that which is filled with water.
Word by word (padaccheda)
Right context एकहलादौ saptamī · ekavacanaRight context पूरयितव्ये saptamī · ekavacanaRight context अन्यतरस्याम् saptamī · ekavacana
- 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").
Full reading
एकहलादौ पूरयितव्ये अन्यतरस्याम्
Pāṇini leaves out words that carry over from earlier sūtras. Expand to see the rule as a reader actually understands it.
Commentary
उद is optionally substituted for उदक before a word beginning with a single consonant and which expresses that which is filled with water.
Thus उदकुम्भः, or उदककुम्भः, उदपात्रम् or उदकपात्रम् ॥ The word एकहलादि means 'a word beginning with a single simple consonant'. The rule does not apply to उदकस्थालम् as the second member begins with a conjunct consonant: nor to उदकपर्वतः, as the पर्वतः is not a vessel which is to be filled.
Śrīśa Chandra Vasu, The Ashtadhyayi of Panini (1897), via ashtadhyayi.com.