Bhashya
यो ह वै संपदं वेद, संपद्गुणयुक्तं यो वेद, तस्य एतत्फ- लम्; अस्मै विदुषे संपद्यते ह; किम्? यं कामं कामयते, स कामः ।किं पुनः संपद्गुणकम्? श्रोत्रं वै संपत् ।कथं पुनः श्रोत्रस्य संपद्गुणत्वमित्युच्यते- श्रोत्रे सति हि यस्मा- त् सर्वे वेदा अभिसंपन्नाः, श्रोत्रेन्द्रियवतोऽध्येयत्वान्; वेद- विहितकर्मायत्तश्च कामाः, तस्मात् श्रोत्रं संपत् ।अतो वि- ज्ञानानुरूपं फलम्, सं हास्मै पद्यते, यं कामं कामयते, य एवं वेद ॥
In plain words
Whoever truly knows attainment — knows it as a quality he himself now carries — gets exactly this reward: it comes to him in full. What reward? Whatever he desires, he gets. But what, then, actually carries this quality of attainment? Hearing does. And why hearing? Because it's only once you can hear that the whole of the Vedas comes together for you at all — hearing is what makes them something you can even study. And every desire depends on the rites the Veda prescribes. That's why hearing is attainment. So the reward matches the knowledge exactly: whatever you desire comes fully to pass for you, once you know this.
Close to the Sanskrit
He who indeed knows Sampad — whoever knows it as endowed with the quality of Sampad — his is this fruit: it comes fully to pass, indeed, for this knower. What? Whatever desire he desires, that very desire [is granted]. What again is that which possesses the quality of Sampad? The ear, verily, is Sampad. How again is it said that the ear has the quality of Sampad? — [The answer is given thus:] the ear being present, since all the Vedas are fully gathered, because [the Veda] becomes fit to be studied for one possessing the organ of hearing; and desires are dependent on the rites enjoined by the Veda; therefore the ear is Sampad. Hence the fruit matches the knowledge: it comes fully to pass for him, whatever desire he desires — he who knows thus.