Skandapurana 6.3.28.17

6.3.28.17

sarpā yantrasthitā ghorāḥ śamye varuṇanairṛtau .
gāyatrī caiva sāvitrī sthite te raśmibandhane .. 28.17 ..

the dread serpents were placed in the mechanism, Varuṇa and Nirṛti in the yoke-pins, / and Gāyatrī and Sāvitrī were stationed in the fastening of the reins;