The Fast of 'Ashura
The fast on the day of 'Ashura is recommended and there are many authentic narrations regarding this. The initial recommendation to observe fasting on that day began when the Prophet SAW observed the Jewish practice when he arrived upon his migration to Madeenah.
From Ibn 'Abbas RA:
When the Prophet SAW arrived in Madinah he saw the Jews fasting (on this day), so when he asked them (about this), they said: "Certainly, this is the day when Allah made Musa victorious and destroyed Fir'aun". So the Prophet SAW said: We have more of a right to Musa than you". So he fasted (that day) and ordered it to be fasted. [Saheeh al-Bukhari]
Remember the principles held by our revered scholars with regards to 'eebadah (worship):
- All forms of worship are HARAM unless there exists textual evidence to prove otherwise
- 'Ibadah is only accepted when there is ikhlas (sincere) and ittibaa' ar-rasul (exemplify the Prophet SAW)
The reward for observing the fast of 'Ashura is as follows:
From Abu Qatadah RA:
The Prophet SAW was asked about observing As-Saum (the fast) on the tenth day of Muharram, and he replied, "It is an expiation for the sins of the previous year." [Saheeh Muslim]
Remember that the fadhilah (rewards) of an 'ibadah may only be derived from textual evidence.
Command to Istibra' & to Avoid Tashabbuh Bil Kuffar
There are numerous evidences of the commands for Muslims to istibra' (oppose) the forms of worship of other religions and to avoid Tashabbuh Bil Kuffar (mimicking the forms of worship of the disbelievers).
Hence, the permissibility given by those who dress in the cloak of ulama' to mimic or be involved in the worships of other religions in the name of integration and pluralism is in fact a sacrifice of the Islamic 'Aqidah.
From Ibn 'Abbas RA:
The Prophet SAW said, "If I remain alive till the next year, I shall also observe fast on the ninth of Muharram." [Saheeh Muslim]
"Observe the fast of 'Ashura but differ from the Jews; fast the day before it (the ninth) or the day after it (the eleventh)" [Ahmad & Bayhaqi, authenticated by Ibn Hajar in "Talkhis Al-Habir"]
Innovations & Falsehood
Like many of the significant dates, events and worships in Islam, there exists innovations and falsehood that are spread to the community. And Muslims are very weak in recognizing these innovations and falsehood because they have not been preached on the importance of the disciplines of "at-tabayyun" and "at-tashfiyyah". (ascertaining & purifying)
These disciplines are generally neglected by da'wah organizations because there exists a stigma and concern that it will decrease its popularity, marketability and its integration within "mainstream Islam".
The problem with today's principles of "all views are okay" and "don't criticize anyone" propagated by mainstream scholars is that an attack onto the Islamic 'aqidah and 'ibadah becomes extremely difficult for today's Muslims to identify.
The practice of the Shi'ite to perform acts of obedience to mourn and honour the death of al-Husayn on the day of 'Ashura is considered an act of evil innovation by our revered scholars.
But because Muslims are not aware of the firm principles and stand of the scholars of Ahlussunnah wal Jamaah against innovations, they are not likely to fully understand why such practices are rejected apart from saying "these are shi'ite practices".
And with Allah is all knowledge.