[Rashi says that the oath “not to force the end” prohibits excessive prayer. In Siman 24 the Rebbe asked how much is too much. In this siman he brings two places where the Yismach Moshe discusses this.
There is another version of the text of the fourth oath, cited by Rashi, that reads “shelo yerachaku” – that they should not push the end of exile further away. Rashi explains, “They should not push the end further away with their sin.”
Now I will explain the third oath, not to force the end. What exactly does this mean? Rashi says that “yidchaku” (force) comes from the word “dochak” (pressure): that the Jews should not pray too much for the end of exile.
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.