The Mother of Sisera is the source of our custom of blow one Hundred blasts on Rosh Hashanah (The Complete Artscroll Machzor for Rosh Hashanah, page 584) Why is our custom based on such an evil personality there where many women who cried in the Rosh Hashanah reading we have two. In Shmuel which we read on Rosh HaShanah, Channah,cannot have a child cries also a second Parsha read on rosh Hashanah in Breishes Hagar (also bad but not as bad) a mother cant watch Yishmael die from lack of water, walks away and cries.So why is it we use this Evil women who was calmed by the other women when told dont worry he is just busy raping and hence has not returned ?
1) I've heard in the name of Rabbi Naftali Peterburger that the crying of Sisera's mother was motivated by, and therefore symbolizes, a feeling which is especially apt for Rosh Hashanah: She was fairly confident that her son was victorious, and yet at the same time there was also a growing, gnawing doubt - maybe he had been defeated? So too on Rosh Hashanah, though we outwardly show confidence that we will be judged favorably, we are reminded by the number of blasts that a successful outcome is not assured.
2) Yad Aharon (692) quotes Rav Shmuel Abuhav that the word 'Sisera' in Tosfos (R.H. 33b, which is the source for the Sisera connection) is a mistake, and was originally 'yenukah'. It is based on the Midrash in Emor that a woman giving birth cries 100 times. This answers another problem with Tosfos as well: there is no source anywhere that Sisera's mother cried 100 times.
Rabbi Pruzanzky quotes Rav Soloveitchik (who I just heard today was referencing Rav Yosef Dov Soloveitchik)
Rav Soloveitchik explained that Sisera’s mother had a routine. She knew he would win, even knew when to expect him back from the battlefield. She knew that he would return triumphant, with the spoils of war, with the laurels of his admirers, with the dread of the vanquished. She was certain – that was her life.
“The mother of Sisera sat by the window, gazing through the lattices…” As she sat there, she started to sob, then to wail, then to mourn. Her certainty – about herself, about her son, about his and her destiny – was an illusion. It wasn’t real. As she uttered the words – “Why does his chariot tarry in coming? Why is he late today?” – she already knew the bitter truth: her world had suddenly changed. There is nothing in life set in stone. Not my life, not my choices, not my fate...
The shofar draws its inspiration not from the anguish of Sisera’s mother, and not because we feel sorry for her, but because we want the shofar to awaken us, to shake us, like it did Sisera’s mother, to grab hold of us and say “life is precious, life is short, there is much to do.” Take nothing for granted, not the least of which one’s religious level in life and one’s aspirations. Everyone can grow and everyone can improve.
The wails of Sisera’s mother are the quality of the sounds of the shofar that penetrate our souls, and her one hundred sobs are the quantity that we require to soften our hearts. We can’t change the world, only our small place in it, beginning with ourselves.