Shariah Ruling addressing Yazid with Radhi-Allahu Anhu
The words “Radhi-Allahu-Anhu” meaning may Almighty-Allah be well pleased with him are used to signify Almighty-Allah’s pleasure. They are used as a form of respect to praise somebody. “Radhi-Allahu-Anhu” is used especially for the Companion & for those pure souls, whose hearts are filled with fear & awe of Almighty-Allah, as Almighty-Allah Most High himself says: Surah Bayyinah-08.
The aforementioned Hadith & the interpretations of the Imaam s make it clear that Yazid was wretched. He changed the Sunnah, he tried to destroy the religion, he insulted the 2 blessed sanctuaries & he insulted the Prophet’s Family. Using “Radhi-Allahu-Anhu” for such a person is to respect him & this is equal to destroying the edifice of Islam. This invites Almighty-Allah’s anger & misguidance. The Holy-Prophet (Peace be upon Him) has declared respecting an innovator equal to lending a h& in destroying the edifice of Islam.
There is a Hadith in Imaam Tabarani’s Mo’jam Ausat (Hadith No: 6263):
Translation: It is narrated on the authority of Hadhrath ‘Aisha Siddiqua (May Almighty-Allah be well pleased with her) that the Holy Prophet (Peace Be upon Him) said: Whoever respects an innovator, verily he helps in destroying Islam.
There is a Hadith in Imaam Baihaqi’s Shu’abul Iman:
Translation: It is narrated on the authority of Hadhrath Anas (May Almighty-Allah be well pleased with him) that The Holy-Prophet (Peace be upon Him) said: When a innovator is respected, Almighty-Allah expresses His anger & because of it, the ‘Arsh trembles. (Shu‘ab Ul Iman, Hadith No: 4692)
Source : Ziaislamic.com