Shama-il Tirmidhi Chapter 042, Hadith Number 012 (292).

Aayeshah Radiyallahu 'Anha reports: "The Quraysh observed the fast of 'Aa-shura in the days of jaahiliyyah (pre-Islaarnic period of ignorance). Rasulullah Sallallahu 'Alayhi Wasallam also observed this fast (before the hijrah as a nafl). (After the hijrah) when he came to Madinah Munawwarah he observed these and commanded the ummah also to observe it. When the command to fast in Ramadaan was revealed, it was proclaimed fard, and the fast of 'Aa-shura became nafl. Those who wished, observed them ('Aa-shura) and those who did not, omitted them.

Commentary
Many narrations have been narrated on the virtues of the saum (fast) of 'Aa-shura. It is stated in a narration in Sahih Muslim that by observing the saum of 'Arafah the sins of two years are forgiven, and by observing the fast of 'Aa-shura the sins of one year are forgiven. Some commentators write that on the day of 'Aa-shura, the taubah (repentance) of Sayyidina Aadam 'Alayhis Salaam was accepted; The boat of Sayyidina Nuh 'Alayhis Salaam docked (after the great floods); Sayyidina Musa 'Alayhis Salaam was saved from Firown, and Firown drowned on this day; Sayyidina 'Eesa 'Alayhis Salaam was born, and raised to the heavens on this day; On this day Sayyidina Yunus 'Alayhis Salaam was freed from the stomach of the fish, and his ummah forgiven; On this day Sayyidina Yusuf 'Alayhis Salaam was taken out of the well; On this day Sayyidina Ayyub 'Alayhis Salaam was cured from his illness; On this day Sayyidina Idriss 'Alayhis Salaam was raised to the sky; On this day Sayyidina Ebrahim 'Alayhis Salaam was born; On this day Sayyidina Sulaymaan 'Alayhis Salaam was given the powers to rule a country; Besides these many other karaamaat (miracles) are mentioned in the commentaries of the ahaadith and books on seerah. Although according to the muhadditheen many questions have been raised on these incidents, there are numerous miracles that have been ascertained. It is said that the wild animals also fast on this day. Allahu Akbar! What a blessed day this is? Yet we waste it in amusements and useless pastimes. Probably it is from among these reasons that, the virtues of this day was well known in the days of jaahiliyyah. Therefore the Quraysh must have observed this fast before the advent of Islaam. When Sayidina Rasulullah Sallallahu 'Alayhi Wasallam came to Madinah Munawwarah, he observed that the Jews, who are from the Ahlul-Kitaab, also observing the fast of Aa-shurah. Sayidina Rasulullah Sallallahu 'Alayhi Wasallam inquired from them the reason for fasting on this day. They replied: 'Allah Ta'alah saved Musa Alayhis salaam on this day from the oppression of Firown (Pharaoh) and also Firown was drowned on this day. In gratitude and happiness Musa Alayhis salaam fasted on this day'. Sayidina Rasulullah Sallallahu 'Alayhi Wasallam replied: "We are more entitled than you to follow Musa Alayhis Salaam". Therefore, Sayidina Rasulullah Sallallahu 'Alayhi Wasallam himself fasted on this day and commanded the Ummah also to fast on this day. This incident is mentioned in the Sahih Muslim. For this reason the Hanafis say this saum (fast) was fard before the command of Ramadhaan was revealed. When the fast of Ramadhaan was ordained these were abrogated. Its merits and the virtues for the forgiveness of one years sins still remain.

Masha-Allah: The original day for the observance of the fast of Aa-shurah is the tenth. In the early periods of Islaam, Sayidina Rasulullah Sallallahu 'Alayhi Wasallam was in agreement with the ahlul-kitaab, as their belief was also from the heavenly revealed religions, and was better than the religion of the mushriqeen, but in the later years the ahlul-kitaab were also opposed in words and deeds, which was necessary due to many factors. Once a sahabi brought this to the notice of Sayidina Rasulullah Sallallahu 'Alayhi Wasallam were upon he replied: "If I remain alive next year I will surely fast on the ninth next year". In another narration it is stated: "Oppose the Jews, observe the fast of the ninth or eleventh" i.e. add a fast to that of the tenth. With this no resemblance or imitation will remain. Therefore, it is advisable not to observe the fast of the tenth only, it is preferable that the fast of the ninth be also added to it, so that one will be fulfilling the commands of both hadith. If the ninth could not be observed then the eleventh should be added.