अद्भिः संस्कृतम्

Operational rule vidhi

The affix यत् comes in the sense of 'sanctified' after the word अपस् in the Instrumental -3rd case in construction, in the छन्दस् (Vedas).

Word by word (padaccheda)

With / by अद्भिः tṛtīyā · bahuvacanaSubstitute / term संस्कृतम् prathamā · ekavacana

With / by Tṛtīyā (3rd case): accompaniment or means.
Substitute / term Prathamā (1st case): in operational rules, the substitute or the thing introduced; in definitions, the term or its referent.

Dotted words are technical terms. Hover or tap one to see its card.

Full reading

अद्भिः संस्कृतम्

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

Commentary

The affix यत् comes in the sense of 'sanctified' after the word अपस् in the Instrumental -3rd case in construction, in the छन्दस् (Vedas).
Thus अप्यम् 'offering purified with water'. As यस्येदमप्यं हविः ॥ The case of construction is indicated in the sutra itself.

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