Shiva Purana

siva.sh/siva-purana/rudra-samhita/146/27

हयास्तस्य तथा प्रोक्ताश्चत्वारो निगमा मुने ।। ज्योतींषि भूषणं तेषामवशिष्टान्यतः परम् ।।२७।।

sanskrit

O sage, the four Vedas are said to be his horses. The remaining planets became their embellishments.

english translation

hayAstasya tathA proktAzcatvAro nigamA mune || jyotIMSi bhUSaNaM teSAmavaziSTAnyataH param ||27||

hk transliteration by Sanscript