सु-वि-निर्-दुर्भ्यः सुपि-सूति-समाः

Karika:-

सुपेः षत्वं स्वपेर्मा भूर्द्विसुष्वापेति केन न ।
हलादिशेषान्न सुपिरिष्टं पूर्वं प्रसारणम् ॥
स्थादीनां नियमो मात्र प्राक्सितादुत्तरः सुपि ।
अनर्थके विषुषुपः षुपिभूतो द्विरुच्यते ॥

The word सुपि is exhibited in the sutra as the form of स्वप् with vocalisation. Thus सुषुप्तः, निःषुप्तः दुः षुप्तः ॥ The word सूति is the क्तिन् ending form of सू; the rule applies to this form only, as सुषूतिः, विषूतिः, निःषूति and दुःषूतिः ॥ The word सम also means the noun सम and not the verb सम स्तम वैक्लव्ये ॥ Thus सुषमम्, विषमम्, निःषमम्, दुःषमम् ॥

Karika- Why is षत्व taught with regard to the सुप् form of स्वप्? Answer:- सुपेः षत्वं स्वपेर्मा भूत्, so that the षत्व change should not take place in स्वप् form, as विस्वप्नः and विस्वप्नक् 3.2.172 ॥ Question:- विसुष्वापेति केन न? For what reason the षत्व change has not taken place in the reduplicate विसुष्वाप, for here also in the reduplicate, is the form सुप्, as विसुप्स्वप्, and then by applying हलादिशेष rule, the प् is elided, and एकदेशविकृतस्थानन्यत्वात् applies? Answer:- हलादि शेषान् न सुपिः, we reduplicate the form स्वप्, as विस्वप्स्वप् and then elide प्, as विस्वस्वप्, and then vocalise, as विसुस्वप् so that there being no form सुप्, there is no षत्व ॥ इष्टं पूर्वं प्रसारणं, in fact, the vocalisation takes place first, and then elision according to an ishti. See (VI 1. 17). Otherwise, in स्वप् स्वप्, as प् is elided, व् would also have been elided. Why is the स of विसुष्वाप not changed to ष by 8.3.64, स्थादीनां नियमो नात्र प्राक् सितादुत्तरः सुपि, the rule 8.3.64 does not apply, because that rule is confined only to verbs up to सित in 8.3.70, while सुप् is after that verb. Moreover the प् of सुप् being elided, the mere सु is अनर्थक, and the maxim is अर्थवद् ग्रहणे नानर्थकस्य ॥ Question:- If this maxim is applied, how do you form विषुषुपुः? Answer:- अनर्थके विषुषुपुः षुपिभूतोद्विरुच्यते, here the form षुप् is doubled, and not सुप् ॥ The root is first joined with the affix वि + स्वप्, then there is vocalisation विसुप्, then there is ष change, as विषुप्, then reduplication, as विषुप्षुप् ॥ Now षत्व being considered asiddha, the doubling should take place first? No, for we have already shown that for the purposes of doubling, the षत्व change is not asiddha 8.2.3 Vartika)),