भो-भगो-अघो-अपूर्वस्य यो ऽशि

Thus भो अत्र, भगो अत्र, अघो अत्र, भो ददाति, भगो ददाति, अघो ददाति ॥ क आस्ते, कय् आस्ते, ब्राह्मणा ददाति, पुरुषा ददाति ॥ The य् is elided by 8.3.19, 8.3.20, 8.3.22 &c. With य, the forms will be भोयत्र, भगोयत्र, अघोयत्र ॥

Why do we say 'when preceded by भो &c'? Observe अग्निरत्र, वायुरत्र ॥ Why do we say 'when followed by a letter of अश् pratyahara'? Observe वृक्षः, प्लक्षः ॥ No, this is no valid counter-example, because no other word follows the visarga; while some word must follow it because the word sanhita 8.2.108 is understood here.

Answer:- If this be so, then अश् is employed in this sutra for the sake of subsequent sutras. Its employment here is superfluous. For letters other than अश् are खर् ॥ Before a खर् letter, the र् will be changed to visarga by 8.3.15; and the यत्व of this rule will be considered as asiddha for the purposes of 8.3.15, so there will necessarily be visarga. Thus अश् serves no purpose in this sutra, but is for the sake of subsequent ones. Thus in 8.3.22, the word हलि must be qualified by the word अश्, namely those consonants only which are in the class अश् ॥ Before any other consonant there will be no elision of य ॥ Thus वृक्षं वृश्चति = वृक्षवृट् ॥ The denominative verb from this will be वृक्षवयति ॥ A secondary derivative from this root, with the affix विच् will be वृक्षव् as in वृक्षव् करोति ॥ Here व् would require elision by 8.3.22, before क्, but it is not so because अशि qualifies हलि ॥

Objection:- If so, why is the word हल् used in that sutra 8.3.22, it would have been better to say हशि सर्वेषाम् instead of हलि सर्वेषाम् ॥

Answer:- The word हल् is used in that sutra for the sake of the subsequent sutra 8.3.23, which applies to all consonants. Had हशि been used in 8.3.22, then in 8.3.23, हलि ought to have been used.

Moreover अशि is used in this sutra, so that rules 8.3.18, 8.3.19 may not apply to वृक्षव् करोति ॥

This sutra applies to रु called र्, therefore not here प्रातरत्र, पुनरत्र ॥,