question #3 Sahih Muslim 1130a, Book 13, Hadith 162 : What historical event is commemorated by fasting on the day of Ashura?

It is the day on which Allah granted victory to Moses and (his people) Bani Isra’il over the Pharaoh and we observe fast out of gratitude to Him. Upon this the Messenger of Allah (ﷺ) said: We have a closer connection with Moses than you have, and he commanded to observe fast on this day.