Srimad-Bhagavatam: Canto 11 - Chapter 1 - Verse 18
Sanskrit:
उच्चै:श्रवास्तुरङ्गाणां धातूनामस्मि काञ्चनम् ।यम: संयमतां चाहम् सर्पाणामस्मि वासुकि: ॥ १८ ॥
ITRANS:
uccaiḥśravās turaṅgāṇāṁdhātūnām asmi kāñcanamyamaḥ saṁyamatāṁ cāhamsarpāṇām asmi vāsukiḥ
Translation:
Among horses I am Uccaiḥśravā, and I am gold among metals. I am Yamarāja among those who suppress and punish, and among serpents I am Vāsuki.