Kaṭha Upaniṣad 10

10

katham ity ucyate -- pītodakā ity ādinā dakṣiṇārthā gāvo viśeṣyante / pītam udakaṃ yābhis tāḥ pītodakāḥ / jagdhaṃ bhakṣitaṃ tṛṇaṃ yābhis tā jagdhatṛṇāḥ / dugdho dohaḥ kṣīrākhyo yāsāṃ tā dugdhadohāḥ / nirindriyā prajananāsamarthā jīrṇā niṣphalā gāva ity arthaḥ / yās tā evambhūtā gā ṛtvigbhyo dakṣiṇābuddhyā dadatprayacchannanandā anānandā asukhā nāmety etad ye te lokās tān sa yajamāno gacchati ///1,1.3 //

Shankara’s Commentary:
Com.—How he thought is explained; the epithet Pitodakah and those which follow describe the cows to be given as rewards. Pítodakah, by which all water has been drunk; jagdhatrinah, by which all grass has been eaten. Dugdhadohah, from which all milk has been milched. Nirindriah (?), not capable of breeding. The meaning is—cows old and useless; giving such cows to the Ritviks for their rewards, the person performing the sacrifice attains those worlds which are joyless, i.e., devoid of happiness.