Jaiminīya Upaniṣad Brāhmaṇa 3.29.2

3.29.2

sa hoccaiśśravāḥ kaupayeyo 'smāl lokāt preyāya
tasmin ha prete keśī dārbhyo 'raṇye mṛgayāṃ cacārāpriyaṃ vininīṣamāṇaḥ /

That Uccaiḥśravas Kaupayeya departed from this world.
When he had died, Keśin Dārbhya roamed in the forest on a hunt, wishing to dispel his grief.