Psalms 29:10

ה' לַמַּבּוּל יָשָׁב וַיֵּשֶׁב ה' מֶלֶךְ לְעוֹלָם

Hashem sat enthroned at the flood; Hashem sits as King forever.

In this Psalm, David speaks of things being as they were at the time of the deluge in Noah’s day. At that time, it was clear that G-d alone ruled. Since everything was washed away, it was apparent that G-d was in sole control.