המתפלל וראה אנס בא כנגדו ראה קרון בא כנגדו לא יהא מפסיק אלא מקצר ועולהOr, in English:
If one was saying Tefillah and he saw a robber29 coming towards him or a carriage coming towards him, he should not break off but curtail it and clear off!There is a famous legend of a miracle that happened to Rashi's mother when she was pregnant with him. To cite from the comic book / graphic novel by Rabbi Berel Wein and Ashley Lazarus, Rashi Hakadosh:
Indeed, one can see the impression in the wall in "Rashi's shul". The biggest nes, of course, is the kvitzas haderech, in which Rashi was born in Troyes, in Northern France, while this event happened in Worms, Germany. Rashi did later travel to Worms, at 17, to learn. And as far as I understand it, he studied in a yeshiva attached to that shul. Hence the name.
(Yes, to be clearer, what I am suggesting is that there is some other reason for that recess, and since it was already called the Rashi shul, people made up this popular legend.)