Some Christians raise the question that the prophet used to keep fast of Ashura in pre-Islamic days till the time the series of revelations to Allah had not yet begun. So why He was adopting the methods of the Pagans

I have read differing positions on this, but I have yet to see any definitive evidence for either positions. It doesn't necessarily have to be Ashura, it could be Arafah or any related fasting that expiates sins. I would like to know whether 'sins' includes all, or only limited to minor ones?

Below are narrations which shows it was abandoned Sahih Muslim .No 2510 > Abd al-Rahman b. Yazid said: When al-Ash'ath b. Qais entered the house > of 'Abdullah he was having his breakfast. He ('Abdullah b. Umar) said: > Abd Muhammad (al-Asha'th), come near to the breakfast. Thereupon he > said: Is not today the day of 'Ashura? He ('Abd al-Rahman) said: Do > you know what the day of 'Ashura is? He said: What is it? He said: It > is a day on which the Messenger of Allaah (sallAllaahu alayhi wa > sallam) used to observe fast before the (fasting) in the month of > Ramadan (became) obligatory. But when it became obligatory the > (fasting of 'Ashura) was abandoned (as compulsory). Abu Kuraib said: > He (the Prophet) abandoned it. Sahih Muslim .No 2511 > This hadith has been narrated from Jarir on the authority of A'mash > with the same chain of transmitters and he said (these words with a > little bit of variation from the previous hadith): When (fasting) in > Ramadan was (made) obligatory, he aban- doned it (the practice of > observing fast on Ashura). Sahih Muslim No 2512 > Qais b Sakan reported that al-Ash'ath b. Qais went to 'Abdullah on the > day of 'Ashura while he was eating. He said: Abu Muhammad, come near > and dine. Upon this he said: I am fasting. Thereupon he said: We used > to observe fast and then (this practice) was abandoned. Sahih Muslim 2514 > Jabir b Samura reported that the Messenger of Allaah (sallAllaahu > alayhi wa sallam) commanded us to observe fast on the day of Ashura > and exhorted us to do it and was particular about it But when > (fasting) in Ramadan was made obligatory, he hence. forth neither > commanded us nor forbade us, nor was he so particular about it Sahih Bukhari: vol 3 . book 31 hadith 116 : Narrated Ibn 'Umar: > The Prophet observed the fast on the 10th of Muharram ('Ashura), and > ordered (Muslims) to fast on that day, but when the fasting of the > month of Ramadan was prescribed, the fasting of the 'Ashura' was > abandoned. 'Abdullah did not use to fast on that day unless it > coincided with his routine fasting by chance. If it is abandoned why Muslims still fast those days?

I want to know if it is true that fasting is recommended by Sunni scholars on the day of Ashura. If so, are they following the Umayyads? Is it a celebration of the day Hussain a.s. the pious grandson of prophet and 3th Imam of Shia was killed? What is the justification they use for recommending this fasting? If they refer to Hadith, who are the chain of narrators of that Hadith? And is that Hadith authentic? Also, it should be mentioned that, in Islam, fasting is a symbol of celebration and Shukr (appreciating God for his gifts)(because fasting at Eid Mabath and Eid Ghadeer is Mustahab and also Umayyads fast at their Celebration for Killing Hussain as at Ashura) . Fasting is Haraam in Eid Qurban and Fitr. But, it is Mustahab in Eid Mabath (start of prophet-hood of prophet) and also in Eid Ghadeer. reference for fasting being symbol of celebration: as evidence I found this Hadith from Imam Reza the 8th Imam of Shia: > سئل الامام الرضا (ع) عن صوم یوم عاشورا، قال: عن صوم ابن مرجانه تسالنی > ذلک یوم صامه الادعیاء من آل زیاد لقتل الحسین (ع) reference of Hadith: تهذیب، 4/301 translate: > Imam Reza a.s. was asked about sawm of Ashura. he said: you asked > about sawm of Ibn Marjaneh (Muaviyeh). in that day Children of Ziyad > took sawm for thir Eid (celebrationg) for killing Hussain s.a. aslo Sahih Muslim in book of sawm narrated from Ibn Masud: when the sawm of Ramazan became obligatory the sawm of Ashura was left. also shia Imams said the sawm of Ashura should be left because when sawm of Ramazan became obligatory it was left and backing to what was left by prophet is Bidat. and also Imams said who celebrate at Ashura Allah will place the Judgement day his sadness day. only Umayyads continued sawm of Ashura and insisted on on it until it became a sunnah for sunni Muslims. fasting is not generally symbol of celebration in Islam. but this is only for Umayyads. because they insisted fasting in this day that was left to keep their celebration day alive every year. and for this fasting and celebration at Ashura are related to each other by Umayyds. and not all Muslims or all sunni Muslims. and any one recommend fasting at Ashura has no base unless following Umayyads because Sahih Muslim says it was left by prophet when Ramazan sawm was obligatory and shia Imams said sawm at Ashura is Makruh.

Wikipedia writes: > Ashura (Day of Remembrance) is the tenth day of Muharram in the Islamic calendar. ... What is the significance of the day of Ashura, and is it obligatory to fast that day?