Jaiminīya Upaniṣad Brāhmaṇa 3.13.7

3.13.7

[iti] nu hiṅkārānāṃ
atha vā ato nidhanam eva
ovā iti dve akṣare
anto vai sāmno nidhanam antas svargo lokānām anto bradhnasya viṣṭapam /

So much for the hiṅkāras.
Now then concerning the finale [nidhana] alone:
'ovā'—these are two syllables.
The finale is the end of the sāman, heaven is the end of the worlds, the highest region of the sun is the end.