Shemos Rabah (15:22): When Hashem said "v'Sera'eh ha'Yabashah" (Bereishis 1:9), the Okainus protested. Hashem kicked it and killed it. When the other waters heard the Okainus' screams, it fled, without knowing to where it flees.

Rashi When You said "Yikavu ha'Mayim" (Bereishis 1:9), the water hastily went "El Mekom Zeh Yasadta Lahem."

Radak: "Yenusun" and "Yechafezun" are future tense in place of past. There are many verses like this. When You said "Yikavu ha'Mayim El Makom Echad" (Bereishis 1:9), the water fled from You, like a slave flees from his master's rebuke, or like a man flees from the rebuke of someone stronger than himself - "Mipnei Ga'aras Chamishah Tanusu" (Yeshayah 30:17).

Malbim: Your rebuke caused them to ascend mountains (verse 8).

Radak: This is like a person who thunders his voice to the point that his colleague is confounded and panicky due to him. So the water did. Your desire was a voice of thunder for them; they were hasty to go to the place of gathering.

Malbim: From the voice of Your thunder they descended to valleys (verse 8).

Malbim: Yes. Nas refers to one who is forced to flee. Nechpaz is one who [is hasty because he] desires a matter. It was Nas from Hashem's rebuke (refer to 104:8:1:2). From the voice of His thunder, "Yechafezun" - it is hasty to go to its natural place (refer to 104:8:2:2).