Bhagavatapurana 4.6.38

4.6.38

kṛtvorau dakṣiṇe savyaṃ pāda-padmaṃ ca jānuni /
bāhuṃ prakoṣṭhe 'kṣa-mālām āsīnaṃ tarka-mudrayā //

38. Resting his lotus-like left foot on the right thigh and the left arm on the left knee, he was seated with a rosary of beads round the right fore-arm and with his hand formed into _Tarka-mudrā_ (a position of the fingers intended to further the light of knowledge).