Who was Rabbi Yisroel Dovid Margulies-Jaffe-Schlesinger, and why was he so exercised about the scourge of square cantorial hats?

Where in this week's parsha do we find a quadruple prohibition in the span of a pasuk and a half?

And why do we conclude vidui by declaring 'v'lo shaveh lanu'?

In this week's installment of 'parsha in halacha' we examine how a small sefer published in 1859 had an outsized impact on halacha and Orthodox Jewish practice for generations to come.