Rig 1.190.01

r̥taṁ ca satyaṁ cābhīddhāttapaso'dhyajāyata। tato rātryajāyata tataḥ samudro arṇavaḥ॥

Truth (of thought) and truthfulness (of speech) were born of arduous penance, thence was nightgenerated, thence also the watery ocean.