Musar su Salmi 98:78

As there are 70 ways to explain the Torah, we are are permitted to approach these problems from a different angle. We will do so by referring to a different Midrash. Commenting on Song of Songs 4,8: תשורי מראש אמנה, Tanchuma Beshalach 10 states that the redemption of the Jews was triggered by G–d's knowledge that they would compose the song of gratitude and extol G–d's virtues as recorded in our portion. In turn the merit that enabled Israel to proclaim this song originally was Abraham's for he had expressed faith in G–d as reported in the Torah (Genesis 15,7) that he believed the promise that he would have children and that their children would inherit the land of Canaan.

Now we understand the Midrash which described the Israelites as עתידין ישראל לומר שירה לעתיד לבא. The Midrash tells us that in the future, עתידין, Israel will give thanks by means of a song as soon as they are told good news, even if the promise has not yet been fulfilled. The level of faith that the Jewish people will display at that time will exceed the level they displayed during the Exodus. This is the meaning of the quotation cited in the Midrash שירה לה' שיר חדש. The quotation continues כי נפלאות עשה, "for He has done wonderful things," although no miracles had yet been performed (Psalms 98,1). [We would have expected the sequence in that verse to be the reverse. Ed.] The quotation of the Midrash from Song of Songs 4,8: תשורי מראש אמנה now also falls into line. Israel is encouraged to start singing מראש, immediately, thus displaying its faith, אמונה.