The Story of Musa ﷺ
The deliverance of Moses and his people from Pharaoh — and the origin of Ashura's fast
Musa ibn Imran (Moses) is among the Ulul-Azm — the five greatest Messengers. Allah sent him to Pharaoh of Egypt to call him to monotheism. Pharaoh rejected him and oppressed his people, so Allah delivered Musa and the Children of Israel and drowned Pharaoh and his army in the sea. This was on the 10th of Muharram — the Day of Ashura. When the Prophet ﷺ arrived in Madina and found the Jews fasting that day, he said: "I have more right to Musa than you" — and he fasted it and commanded it (Bukhari & Muslim).
Musa's story appears in the Qur'an more than any other prophet's — in Surah al-Baqara, al-A'raf, Yunus, Ta-Ha, ash-Shu'ara', al-Qasas, and many more. Read Surah Ta-Ha and Surah al-Qasas for the full narrative.