Rashi in his commentary on Hoshanos (printed in Siddur Otzar Hatefilos, as well as in Siddur Beis Yaakov) explains the words “G-d of salvations, in the four oaths” as a reference to the oaths of Shir Hashirim. We ask Hashem: Grant us salvation, for You have made us swear not to rebel against the nations, and we are keeping your oath in exile and bearing the yoke of exile. And You said, “Until it is desired.” Now may it be Your will and Your desire to save us from the hands of the nations.