Shaykh Muqbil bin Haadee (rahimahullaah) stated about Shaykh Rabee bin Haadee:

From the most insightful of people of the jamaa'aat (partisan groups) and the taint (dakhan) of the jamaa'aat in this era, is the brother, the Shaykh, Rabee' bin Haadee (may Allaah protect him). To whomever Shaykh Rabee says that he is a hizbee, then after the passing of days it will be uncovered to you that he is hizbee, you will remember that. At the beginning of his affair, a man may conceal himself (in terms of what he is upon), he does not like to be uncovered, however when he becomes strong and gains followers and (he is certain that any) speech about him will not harm him if he now openly manifests what he has with him, so I advise the reading of his books (Shaykh Rabee's) and benefiting from them - may Allaah protect him.

Source: In the cassette (الأسئلة السنية لعلاّمة الديار اليمنية، أسئلة شباب الطائف) and as published in (الثناء البديع من العلماء على الشيخ ربيع) by Shaykh Khalid al-Dhufayree. Shaykh Muqbil has described perfectly how these people behave, those who are from the jamaa'aat or sympathetic towards them, then they infiltrate the ranks of Ahl al-Sunnah, pretend to be upon the way of the Salaf, show apparent love for the Scholars, appear to defend the Sunnah, and then once they have gathered followers, or have got on the kursee (chair), they bring out into the open what they may have been concealing of false principles and hatred and resentment of the Scholars. Ironically, this speech of Shaykh Muqbil is not far off in describing al-Ma'ribee and al-Hajuri (website), both of whom Shaykh Rabee described with inhiraaf.