Bhagavatapurana 2.10.29

2.10.29

āditsorannapānānām āsan kukṣyantranāḍayaḥ /
nadyaḥ samudrāśca tayostuṣṭiḥ puṣṭistadāśraye //

29. When He thought of taking in food and drink, the stomach, entrails, and passages were formed and the presiding deities are respectively Rivers and Seas; the satisfaction and nourishment of the two sets of organs depend upon the organs and the presiding deities.