Nittel Nacht (night)
Nittel Nacht is a name given to Christmas Eve by Jewish scholars in the 17th century, Jews were forbidden from appearing in public during the high Christmas holidays, and as such the day marked the beginning of a siege of sorts for certain Jewish populations. “Studying the Torah is forbidden”, Passing the time playing card games or chess is also popular.
After the advent of the Gregorian Calendar, Orthodox Christians and Catholic Christians observed Christmas Eve on two separate dates; this led to Rabbinic debate, and Nittel Nacht is observed in accordance with the local Christian community. Certain pious Jews observed Nittel Nacht twice each year. December 25 and January 6.