असूर्यललाटयोर्दृशितपोः

Operational rule vidhi

The affix खश् comes after the verb दृश् 'to see' and तप् 'to heat' when असूर्य and ललाट are the words in composition with it as object.

Word by word (padaccheda)

Right context असूर्य- ललाटयोः saptamī · dvivacanaTarget दृशि- तपोः 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

असूर्य-ललाटयोः दृशि-तपोः

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 verb दृश् 'to see' and तप् 'to heat' when असूर्य and ललाट are the words in composition with it as object.
Thus असूर्य + दृश् + खश् = असूर्यम्पश्यः; as असूर्यम्पश्या राजदारा 'the king's wives not even seeing the sun' (being shut up in the harem, and so having no opportunity of seeing the sun, that is, they are so well protected that even the sun cannot see them, much less any irreverent gaze).

So also ललाटन्तपः 'heating the fore-head' (such as the sun).

The word असूर्य is an incomplete or impossible compound, as the negative अ applies to the verb दृश् and not to the word सूर्य. This is in opposition to the rule of samartha pada vidhi 2.1.2.

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