When the Prophet arrived at Medina, the Jews were observing the fast on 'Ashura' (10th of Muharram) and they said, "This is the day when Moses became victorious over Pharaoh," On that, the Prophet said to his companions, "You (Muslims) have more right to celebrate Moses' victory than they have, so observe the fast on this day."

Allah's Apostle said, "The one who looks after and works for a widow and for a poor person is like a warrior fighting for Allah's Cause." (The narrator Al-Qa'nabi is not sure whether he also said "Like the one who prays all the night without slackness and fasts continuously and never breaks his fast.")

Allah's Apostle deputed me to keep Sadaqat (al-Fitr) of Ramadan. A comer came and started taking handfuls of the foodstuff (of the Sadaqa) (stealthily). I took hold of him and said, "By Allah, I will take you to Allah's Apostle ." He said, "I am needy and have many dependents, and I am in great need." I released him, and in the morning Allah's Apostle asked me, "What did your prisoner do yesterday?" I said, "O Allah's Apostle! The person complained of being needy and of having many dependents, so, I pitied him and let him go." Allah's Apostle said, "Indeed, he told you a lie and he will be coming again." I believed that he would show up again as Allah's Apostle had told me that he would return. So, I waited for him watchfully. When he (showed up and) started stealing handfuls of foodstuff, I caught hold of him again and said, "I will definitely take you to Allah's Apostle. He said, "Leave me, for I am very needy and have many dependents. I promise I will not come back again." I pitied him and let him go.

In the morning Allah's Apostle asked me, "What did your prisoner do." I replied, "O Allah's Apostle! He complained of his great need and of too many dependents, so I took pity on him and set him free." Allah's Apostle said, "Verily, he told you a lie and he will return." I waited for him attentively for the third time, and when he (came and) started stealing handfuls of the foodstuff, I caught hold of him and said, "I will surely take you to Allah's Apostle as it is the third time you promise not to return, yet you break your promise and come." He said, "(Forgive me and) I will teach you some words with which Allah will benefit you." I asked, "What are they?" He replied, "Whenever you go to bed, recite "Ayat-al-Kursi"-- 'Allahu la ilaha illa huwa-l-Haiy-ul Qaiyum' till you finish the whole verse. (If you do so), Allah will appoint a guard for you who will stay with you and no satan will come near you till morning. " So, I released him. In the morning, Allah's Apostle asked, "What did your prisoner do yesterday?" I replied, "He claimed that he would teach me some words by which Allah will benefit me, so I let him go." Allah's Apostle asked, "What are they?" I replied, "He said to me, 'Whenever you go to bed, recite Ayat-al-Kursi from the beginning to the end ---- Allahu la ilaha illa huwa-lHaiy-ul-Qaiyum----.' He further said to me, '(If you do so), Allah will appoint a guard for you who will stay with you, and no satan will come near you till morning.' (Abu Huraira or another sub-narrator) added that they (the companions) were very keen to do good deeds. The Prophet said, "He really spoke the truth, although he is an absolute liar. Do you know whom you were talking to, these three nights, O Abu Huraira?" Abu Huraira said, "No." He said, "It was Satan."

The Prophet said, "There is a gate in Paradise called Ar-Raiyan, and those who observe fasts will enter through it on the Day of Resurrection and none except them will enter through it. It will be said, 'Where are those who used to observe fasts?' They will get up, and none except them will enter through it. After their entry the gate will be closed and nobody will enter through it."

Yahya related to me from Malik from Ibn Shihab from Urwa ibn az- Zubayr from A'isha, the wife of the Prophet, may Allah bless him and grant him peace, that the Messenger of Allah, may Allah bless him and grant him peace, prayed in the mosque one night and people prayed behind him. Then he prayed the next night and there were more people. Then they gathered on the third or fourth night and the Messenger of Allah, may Allah bless him and grant him peace, did not come out to them. In the morning, he said, "I saw what you were doing and the only thing that prevented me from coming out to you was that I feared that it would become obligatory (fard) for you." This happened in Ramadan.

Salama b. al-Akwa' (Allah be pleased with him) reported that the Messenger of Allah (may peace be upon him) sent a person of the tribe of Aslam on the day of 'Ashura and commanded him to declare to the people to observe fast in case they had not observed it, and to complete fast till evening if they had taken food

The Prophet said, "Whoever wishes may fast on the day of 'Ashura'."