English translation
2443. Ibn Umar said: “Āshūrā’ was a day we used to fast during Jāhiliyyah. When (the obligation of fasting) Ramaḍān was revealed, the Messenger of Allāh ﷺ said: “This day is among Allāh’s days,” so whoever wanted to, he would fast it, and whoever wanted to, he would leave it.” (Sahīh)
