What is the meaning of "Amar Hashem mi'Bashan Ashiv"?
Rashi: He promised to return us from the mighty ones of Bashan.
Radak: I will return the enemies from Eretz Yisrael, like I returned the Egyptians from the depths of the sea. I.e. just like they drowned and did not return, so the camp of Melech Ashur - "they were all dead bodies" (Melachim II, 19:35). Bashan is in Eretz Yisrael Gil'ad; it was the start of Melech Ashur's war against Yisrael. Pul Melech Ashur conquered that entire land.
Malbim: Hashem tells [the angel of] death, here you will not crush. Rather, I will return the remnants of the enemy from Bashan. They will flee from there to Chutz la'Aretz, where the angel of death rules.
What do we learn from "Ashiv mi'Metzulos Yam"?
Gitin 57b: If one is being taken on a boat for sexual exploitation, and drowns himself to avoid this, Hashem will return him from the depths of the sea, to bring him to the world to come.
Rashi: He promised to return us from islands.
Radak: Refer to 68:23:1:2.
Malbim: I will return the enemy also from Yam ha'Melach, which is also the eastern border. They fought also there - "Yo'av va'Yach Es Edom b'Gei Melach" (60:2). Gei Melach was initially a sea; its place became a canyon of salt, as is known. I will return them from there to Chutz la'Aretz, where the angel of death rules.
