After a word in the Instrumental -3rd case in construction, an affix -- prāgdīvyato'ṇ [[4.1.83]] etc., comes in the sense of 'enounced by him'.,
The word प्रोक्तं means प्रकर्षेणोक्तं 'preeminently spoken'. It should be distinguished from the word कृत meaning 'done or made'. For the sense of कृतं has been already taught in the sutra कृते ग्रन्थे 4.3.16. Thus अन्येन कृता माथुरेण प्रोक्ता = माथुरी वृत्तिः ॥ पाणिनीयम् 'the system of grammar enounced by Panini' आपिशलम्, काशकृत्स्नम् ॥
Works like Chhandas which were made (कृतं) by nobody, but which were promulgated (प्रोक्तं) from time of time by inspired commentators, may be quoted as examples of the application of this sutra. Or it may apply to the case of a book whose author is another, but whose promulgator or expounder is another. In short, speaking roughly, प्रोक्त is a 'revelation', and कृतः is a 'composition', once a revealer or prophet, the other an author.
According to some, this sutra is almost a superfluity. They argue thus: The word प्रोक्त is formed by adding प्र to वच and means 'to lecture' 'he teach', and also the 'means of such teaching &c'. In the first sense of 'lecturing or teaching', the affix is not found. For in every village there are persons who teach or lecture upon Katha, Kalapa &c. For example सुशर्मन् may be such a lecturer, but we do not say सुशर्मणा प्रोक्तं काठकं = सौशर्मणम् ॥ Moreover, where we find this affix employed, it is with regard to Books, for which the rule कृते ग्रन्थे is sufficient. If it be said that it should be taught for the Chhandas: that is also unnecessary, as the Vedas are not कृत but eternal, the agent only remembers them. If it be said, it refers to the sense of the Vedas, the same objection applies as to the first. But the letter of the Veda is not eternal, it is the sense that is eternal. Therefore the Rishis who revealed, for the first time, at the beginning of a Kalpa, the sense of the Veda, in appropriate language will be called its promulgators, and the works so revealed will be named after such Rishis, as काठकम्, कालापकम् and मौदकम् ॥ This sutra, however, is confined to those cases where the author of the book is one person and its promulgator is another : as माथुरी वृत्तिः ॥,