हन्तेर्जः

Operational rule vidhi

The 'हन्' धातु gets the 'ज' आदेश when followed by the हि-प्रत्यय of लोट्लकार.

Word by word (padaccheda)

Target हन्तेः ṣaṣṭhī · ekavacanaSubstitute / term जः prathamā · ekavacana

Target Ṣaṣṭhī (6th case): names what gets replaced, "in place of X" (1.1.49 षष्ठी स्थानेयोगा).
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.

हन्तेः जः

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

As a rewrite rule (sketch from case endings)

हन्तेः → जः

Replace hanteḥ with jaḥ. Inherited words (anuvṛtti) may add further conditions.

ज is substituted for हन् before the Imperative affix हि।
Thus जहि शत्रून् ॥

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