Yar... I do not trust anything if there's no dalil. So I did not trust anything I read from kedaisiber where NI linked regarding Puasa Asyura. Instead I googled on 'hadith hari asyura' as I have heard before of hadiths regarding this pecial day which falls on 10 Muharram, which this year 1430H falls on Wednesday, 7 Jan 2009M.

Anyway the following is taken from a blog which was indeed taken from muslimspace. I hope it is of benefit for you.

I urge Muslims reading this to fast on the Day of Asyura and apart from praying for your sins of the past year be forgiven, do pray too for our dear Muslim brothers and sisters in Palestine. Once before, Allah saved the Children of Israel from their enemy (in Egypt ) and so Prophet Musa fasted on this day giving thanks to Allah. May this time Allah saves the Children of Israel from Palestine as well as the Children of Palestine from Israel. I do not wish to point fingers on who's right and who's wrong. I'm not the one going through experiencing the 'war' either as an Israeli or as a Palestinian, so I feel that I have no hak, or right in judging who's right and who's wrong. Allah is best of judge and the most just, may He save all innocent lives and send hidayah to those who do wrong, may they stop hurting and killing others, innocent or not.

From muslimspace:

First of all, it is very important to make it clear that fasting on the day of `Ashura' – the 10th of Muharram- is of great merits in Islam. The Prophet (peace and blessings be upon him) said, "Fasting the day of `Ashura' (is of great merits), I hope that Allah will accept it as an expiation for (the sins committed in) the previous year" (Muslim).



Later, before the end of his life, the Prophet (peace and blessings be upon him) told Muslims to add the 9th day also. Thus, it is recommended to fast on both the 9th and 10th of Muharram.

Moreover, in his well-known book, Fiqh As-Sunnah, the late Sheikh Sayyed Sabiq states:



Abu Hurayrah reported: "I asked the Prophet: 'Which Prayer is the best after the obligatory Prayers?' He said: 'Prayer during the mid of the night.' I asked: 'Which fasting is the best after that of Ramadan?' He said, 'The month of Allah that you call Muharram'" (Ahmad, Muslim, and Abu Dawud).

Fasting the Day of `Ashura' is not to mourn the martyrdom of imam Husain (may Allah be pleased with him). We deeply respect Imam Husain's martyrdom, we honor his glorious act of sacrifice for the sake of Islam. He gave us a great example of truth, courage and piety. But we also feel pain and grief in our hearts for his assassination at the hand of some hypocrites who took Islam as a pretext to commit their crime. They fought and killed Allah's Messenger's beloved and blessed grandson and his family. This was the most heinous and shameful crime that was committed for the sake of political power. This tragic event took place in the year 61 AH or 680 CE. However, the tradition of `Ashura' fasting is very ancient and it goes back to a long time before imam Husian.



It is reported in the Sahih of Imam Al-Bukhari and other authentic collections of hadith that the Prophet (peace and blessings be upon him) and his Companions used to fast on the 10th day of Muharram while they were in Makkah (before the hijrah).



It was a day on which people of Makkah used to change the covering (kiswah) of the Ka`bah. Quraysh also used to fast on this day. (Al-Bukhari, hadith 1489 and 1760)



After the hijrah when the Prophet (peace and blessings be upon him) came to Madinah, he found that the Jews of Madinah also used to observe this day with fasting. The Prophet (peace and blessings be upon him) asked them the reason of their fasting on this day. They said, "This is a blessed day. On this day Allah saved the Children of Israel from their enemy (in Egypt ) and so Prophet Musa fasted on this day giving thanks to Allah." The Prophet (peace and blessings be upon him) said, "We have more claim to Musa than you." He fasted on that day and commanded Muslims to fast on this day. (Al-Bukhari, hadith 1865)



In another report it is mentioned that Jews of Madinah used to hold a feast on this day. The Prophet (peace and blessings be upon him) told his Companions to fast instead. (Al-Bukhari, hadith 1866)



`Ashura' fasting was obligatory (fard) in the beginning. In the second year of hijrah (624 CE) when Allah's command came that Muslims should fast the whole month of Ramadan, the Prophet (peace and blessings be upon him) then sent someone to announce to people that fasting of `Ashura' had become voluntary (nafl). This indicates that whosoever wishes to fast, may fast and whosoever does not want to fast, there will be no blame on him/her.



Imam at-Tirmidhi mentioned that ibn `Abbas (may Allah be pleased with them both) used to say that we should fast on two days: the 9th and 10th of Muharram to distinguish ourselves from the Jewish community. (At-Tirmidhi, Hadith 686)





Mu`awiyyah ibn Abi Sufyan reported that he heard the Messenger of Allah say: "Concerning the day of `Ashura', it is not obligatory upon you to fast on it as I do. Whoever wishes may fast and whoever does not wish to is not obliged to do so" (Al-Bukhari and Muslim).



It is noteworthy that Muslim scholars have stated that fasting of `Ashura' is of three levels as follows:



1. fasting for three days, i.e., on the 9th, 10th, and 11th of Muharram,



2. fasting the 9th and 10th of Muharram, and



3. fasting only the 10th of Muharram