Shaykh al-Islam Abul-‘Abbas Ibn Taymiyyah denounced and refuted Rafidis AND Nasibis:

Ibn Taymiyah discussed the two misguided groups who were in Kufah, Iraq, both of whom took ‘Ashura’ as a festival because of their bid’ah:

“Because of the killing of al-Husayn (may Allah be pleased with him), Shaytan caused the people to introduce two innovations: the innovation of mourning and wailing on the day of ‘Ashura’, by slapping the cheeks, weeping, and reciting eulogies. … and the innovation of rejoicing and celebrating. … So some introduced mourning and others introduced celebration, so they regarded the day of ‘Ashura’ as a day for wearing kohl, doing ghusl, spending on the family, and making special foods. … And every innovation is a misguidance. None of the four imams of the Muslims or any other (scholars) regarded either of these things as mustahabb. (Minhaj al-Sunnah,4/554)

“The Rafidi group made an outward show of allegiance to the Ahl al-Bayt although inwardly they were either heretics and disbelievers or ignorant and bound by whims and desires. The Nasibi group hated ‘Ali (may A) and his companions, because of the troubles and killings that had occurred. Some others either Nasibis (Nawasib) who oppose and have enmity towards al-Husayn and his family or ignorant people who try to fight evil with evil, corruption with corruption, lies with lies and bid’ah with bid’ah opposed them (Rafidis) by fabricating reports in favor of making the day of ‘Ashura’ a day of celebration, by wearing kohl and henna, spending money on one’s children, cooking special dishes and other things that are done on ‘Eids and special occasions. These people took the day of ‘Aashura’ as a festival like ‘Eid, whereas the others took it as a day of mourning. BOTH are wrong, and both go against the Sunnah, even though the other group (the Rafidis) are worse in intention, more ignorant, and more plainly wrong… (al-Fatawa al-Kubra)

Ashura – Between Rafidi and Nasibi Bid’ah

To counteract the extreme position of some of the Rafidah Shia, the Nawasib (haters of the Ahlul-Bayt) took this day as a day of celebration. They celebrated this day by wearing new clothes, cooking special food and spending extra money on their family.

The Shia and the Nawasib opposed each other by introducing an innovation in the religion. So while one group lamented and mourned on this day the other group celebrated and made it a day of ‘Id. As for the Ahl al-Sunnah they oppose both of these groups, neither making it a day of celebration nor a day of mourning.

Ahl al-Sunnah have not taken the day of ‘Ashura as a day of celebration and ‘Id, this is baseless accusations of the Shia and a frankly ignorant one. Muslims feast on ‘Id days, as a matter of fact, fasting is prohibited on days of celebration (‘Id) in Islam, yet Sunni ‘Ashura is all about fasting, it can be thus described as a thanksgiving to Allah.

Ibn Taymiyyah writes in his Fatawa:

“As for cooking special foods, wearing new clothes, applying kohl, spending extra money on the children, doing special prayers, having a special bath… all of these are reprehensible innovations in the religion which the Messenger of Allāh (ṣallallāhu ‘alayhi wa sallam) never practiced nor did the rightly guided caliphs, and neither was it recommended by any of the great Imāms such as, Mālik, at-Thawrī, al-Layth b. Sād, Abū Hanīfah, al-Awzāī, ash-Shāfi’ī, Aḥmad b. Hambal, Ishāq b. Rāhūyeh (raḥimahum Allāhu), nor by other such scholars. Rather some of the later followers started to instruct in some of these things and claimed that there were some authentic aḥādith supporting their view. But these people are clearly mistaken and are in error according to the people of knowledge.