הָ֤פַךְ יָ֨ם ׀ לְֽיַבָּשָׁ֗ה בַּ֭נָּהָר יַֽעַבְר֣וּ בְרָ֑גֶל שָׁ֝֗ם נִשְׂמְחָה־בּֽוֹ׃
Er wandelte das Meer in Trockenheit, durch den Strom zogen sie zu Fuße. Damals freuten wir uns sein.
Rashi on Psalms
there it rejoiced with it I found: There was a thing with which the sea rejoiced, i.e., that the sea saw the Holy One, blessed be He.