SB 9.4.37
pratinandya sa tam yacñam
kartum avasyakam gatah
nimamajja brhad dhyayan
kalindi-salile subhe
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Durvasa Muni gladly accepted the request of Maharaja Ambarisa, but to perform the regulative ritualistic ceremonies he went to the river Yamuna. There he dipped into the water of the auspicious Yamuna and meditated upon the impersonal Brahman.